| Word | Description |
| S/Key | A security mechanism that uses a cryptographic hash function to generate a sequence of 64-bit, one-time passwords for remote user login. The client generates a one-time password by applying the MD4 cryptographic hash function multiple times to the user's secret key. For each successive authentication of the user, the number of hash applications is reduced by one. |
| SA | 1. System Administrator. 2. The system administrator account installed with Microsoft SQL Server. This system administrator account has the username "sa". 3. Software Assurance. Specifically the Software Assurance for Volume Licensing scheme run by Microsoft. |
| Safe Mode | Safe Mode is a way for the Windows operating system to run with the minimum system files necessary. It uses a generic VGA display driver instead of the vendor-specific driver, which means you will likely be working with only 16 colors in a resolution of 640x480. Safe Mode also turns off all third-party drivers for other peripherals such as mice, keyboards, printers, and scanners. In basic Safe Mode, networking files and settings are not loaded, meaning you won't be able to connect to the Internet or other computers on a network. So why would I ever want to boot in Safe Mode? Well, that's a good question. Sometimes, Windows may not fully load after an unexpected crash and the only way to get the computer to boot is to use Safe Mode. Once you have successfully booted the computer in Safe Mode, you can run a disk utility program to repair corrupted files or directories on the hard drive. You can also reboot into Safe Mode to see your display when you get a "Sync Out of Range" message on your screen. There may also be times when your computer is performing sluggishly and becomes annoyingly slow. Booting into Safe Mode will allow you to diagnose the problem and determine which files are slowing down the computer. When calling technical support, the support person may ask you to boot into Safe Mode to begin the troubleshooting. To boot your Windows computer into Safe Mode, hold down the F8 key while the computer is starting up. Then select Safe Mode from the list of boot options. |
| Safe raw disk file | A file containing access privilege information that controls a virtual machine's read/write access to partitions on a raw disk. Proper use of this file prevents dual-boot users from accidentally trying to run the host operating system again as a guest or from another guest operating system that the virtual machine was not configured for. Safe raw disk files can also prevent accidental writes to raw disk partitions from badly behaved operating systems or applications. Safe raw disk files can be created by the Configuration Wizard or the Configuration Editor. |
| SAM | Security Accounts Manager. |
| Samba | Most people know of samba as a type of rhythmic dance music from Brazil that uses a 2/4 time signature. In the computer world, samba has a different meaning but is no less exciting (if you are a computer nerd). Samba is an open-source software implementation of the SMB networking protocol used by Windows computers. (If you look closely, you can see the correlation between the two names.) Samba allows other computer platforms, such as Mac OS X, Unix, Linux, IBM System 390, and OpenVMS to interact with Windows computers on the same network. This includes sharing files and using shared devices such as printers connected to other computers within the local network. Because SMB was developed only for Windows, without Samba, other computer platforms would be isolated from Windows machines, even if they were part of the same network. Fortunately, Samba helps different types of computers work together as if they were all based on the same platform. This gives network administrators the freedom to choose multiple types of computers systems when setting up a network. |
| Sample | A sample is a digital representation of an analog signal. Both digital video and digital audio files are created using samples. The quality of the sample is determined by the sampling rate, or the bit rate the signal is sampled at. What we see and hear in the real world is in analog format (our bodies process analog information). Computers, on the other hand, can only understand digital information. Therefore, audio and video signals must be converted to a digital format in order to be stored on a computer or saved to a CD or DVD. The converted data is called a sample. The term "sample" is often used to refer to short audio clips used for playing back sounds. For example, a violin sound or a bird chirp may be sampled and then played back from a digital keyboard (or synthesizer). However, samples can refer to entire songs or movies, since the information is technically one long sample. To learn more about how samples are created, view the definition of sampling, which is the process of recording and creating digital samples. |
| Sampling | Before digital recording took over the audio and video industries, everything was recorded in analog. Audio was recorded to devices like cassette tapes and records. Video was recorded to Beta and VHS tapes. The media was even edited in analog format, using multichannel audio tapes (such as 8-tracks) for music, and film reels for video recordings. This method involved a lot of rewinding and fast-forwarding, which resulted in a time-consuming process. Fortunately, digital recording has now almost completely replaced analog recording. Digital editing can be done much more efficiently than analog editing and the media does not lose any quality in the process. However, since what humans see and hear is in analog format (linear waves of light and sound), saving audio and video in a digital format requires converting the signal from analog to digital. This process is called sampling. Sampling involves taking snapshots of an audio or video signal at very fast intervals ? usually tens of thousands of times per second. The quality of the digital signal is determined largely by the sampling rate, or the bit rate the signal is sampled at. The higher the bit rate, the more samples are created per second, and the more realistic the resulting audio or video file will be. For example, CD-quality audio is sampled at 44.1 kHz, or 44,100 samples per second. The difference between a 44.1 kHz digital recording and the original audio signal is imperceptible to most people. However, if the audio was recorded at 22 kHz (half the CD-quality rate), most people would notice the drop in quality right away. Samples can be created by sampling live audio and video or by sampling previously recorded analog media. Since samples estimate the analog signal, the digital representation is never as accurate as the analog data. However, if a high enough sampling rate is used, the difference is not noticeable to the human senses. Because digital information can be edited and saved using a computer and will not deteriorate like analog media, the quality/convenience tradeoff involved in sampling is well worthwhile. |
| SAN | 1. Storage Area Network. cf. DAS and NAS. 2. Standard Address Number. A unique seven digit number used to identify a specific address of an organisation in the publishing industry. |
| Sandbox | In computer security, a sandbox is a security mechanism for separating running programs. It is often used to execute untested code, or untrusted programs from unverified third-parties, suppliers and untrusted users. The sandbox typically provides a tightly-controlled set of resources for guest programs to run in, such as scratch space on disk and memory. Network access, the ability to inspect the host system or read from input devices are usually disallowed or heavily restricted. In this sense, sandboxes are a specific example of virtualization. Some examples of sandboxes are: Applets are self-contained programs that run in a virtual machine or scripting language interpreter that does the sandboxing. In application streaming schemes, the applet is downloaded onto a remote client and may begin executing before it arrives in its entirety. Applets are common in web browsers, which use the mechanism to safely execute untrusted code embedded in web pages. Three common applet implementations—Adobe Flash, Java applets and Silverlight—provide (at minimum) a rectangular window with which to interact with the user and some persistent storage (at the user's permission). A jail is a set of resource limits imposed on programs by the operating system kernel. It can include I/O bandwidth caps, disk quotas, network access restrictions and a restricted filesystem namespace. Jails are most commonly used in virtual hosting. Rule-based Execution gives users full control over what processes are started, spawned (by other applications), or allowed to inject code into other apps and have access to the net. It also can control file/registry security (What programs can read and write to the file system/registry) As such, viruses and trojans will have a less likely chance of infecting your PC. The SELinux and Apparmor security frameworks are two such implementations for Linux. Virtual machines emulate a complete host computer, on which a conventional operating system may boot and run as on actual hardware. The guest operating system is sandboxed in the sense that it does not run natively on the host and can only access host resources through the emulator. Sandboxing on native hosts: Security researchers rely heavily on sandboxing technologies to analyse malware behaviour. By creating an environment that mimics or replicates the targeted desktops, researchers can evaluate how malware infects and compromises a target host. Capability systems can be thought of as a fine-grained sandboxing mechanism, in which programs are given opaque tokens when spawned and have the ability to do specific things based on what tokens they hold. Capability based implementations can work at various levels, from kernel to user-space. An example of capability-based user-level sandboxing would be HTML rendering in Google Chrome. |
| SAS | Serial Attached SCSI. |
| SATA | SATA Serial ATA (Serial AT Attachment). See Serial ATA. |
| satellite transmission | A method of data transmission; the sender beams data up to an orbiting satellite and the satellite beams the data back down to the receiver. |
| Scalability | The ability to grow with your needs. A scalable software package means that you only buy the parts you need, and that it has the ability to grow by adding on as you do. |
| Scalable | Applications or systems that are able to scale to large amounts of users. For example, a database that completely locks out every other user when someone is using it is NOT scalable. The computer system that runs ATM and bank transactions must be highly scalable. It is often misspelled as “Scaleable,” and is used in many product names. |
| Scalable Link Interface (SLI) | For other uses, see SLI. Scalable Link Interface Manufacturer Nvidia Type Multi-GPU Scalable Link Interface (SLI) is a brand name for a multi-GPU solution developed by Nvidia for linking two or more video cards together to produce a single output. SLI is an application of parallel processing for computer graphics, meant to increase the processing power available for graphics. The name SLI was first used by 3dfx under the full name Scan-Line Interleave, which was introduced to the consumer market in 1998 and used in the Voodoo2 line of video cards. After buying out 3dfx, Nvidia acquired the technology but did not use it. Nvidia later reintroduced the SLI name in 2004 and intended for it to be used in modern computer systems based on the PCI Express (PCIe) bus. However, the technology behind the name SLI has changed dramatically. |
| SCANDISK | SCANDISK or ScanDisk is a utility in MS-DOS and Microsoft Windows systems which checks and repairs file systems and bad clusters on the hard drive. It was introduced in MS-DOS version 6.2. Previous versions of MS-DOS supplied only the simpler, purely text-based program CHKDSK. ScanDisk included a more user-friendly interface than MS-DOS CHKDSK, more command-line and other configuration options,[1][2] and the ability to detect and sometimes recover from physical errors on the disk.[3] Unlike CHKDSK, ScanDisk would also repair crosslinked files.[4] In Windows 95 onwards, SCANDISK also had a graphical user interface, although the text interface continued to be available for use in single-tasking ("DOS") mode.[5][6] SCANDISK can't check NTFS disk drives and therefore isn't available for computers running NT based (including Windows 2000, Windows XP, etc.) versions of Windows: a newer CHKDSK is provided instead (not to be confused with the older MS-DOS CHKDSK). On Unix-like systems there are tools like "fsck_msdosfs" to do the same task.[7] |
| Scanner | A scanner is an input device that scans documents and images, which can be imported into a computer. They are available in flatbed or sheet-fed versions and are usually connected via a high-speed USB port. OCR software can be used to recognize text documents imported from a scanner. |
| Scavenging | Searching through data residue in a system to gain unauthorized knowledge of sensitive data. |
| scene graph | scene graph The scene graph is the data structure defined in VRML. Files using a WRL extension describe the three-dimensional world, including the objects it contains, their properties, and how they interact. As in HTML, developers can link external media--such as graphic textures or sound files. Also like HTML, scene graph files are simple text files. Work is under way to create a binary (nontext) file format for VRML that should dramatically decrease scene-graph file sizes. See also: VRML |
| screen reader | A software program that translates text on a Web page into audio output; typically used by individuals with vision impairment. |
| Screensaver | A program that displays an image, animation, or just a blank screen on a computer after no input has been received for a certain length of time. Screensavers were originally designed so that images would not be burned into the phosphors of older CRT screens, but soon turned into a source of entertainment. Complex screensavers can use a good deal of CPU power to run, and should be kept off of servers. Screensavers are largely unnecessary today as CRT screens are much more resistant to burn-in. |
| Screenshot | A screenshot, or screen capture, is a picture taken of your computer's desktop. This may include the desktop background, icons of files and folders, and open windows. It may also include whatever is being displayed by currently running programs. Screenshots are and easy way to save something you see on the screen, such as an open window, image, or text article. However, because screenshots are saved in an image format, the text saved in a screenshot will not be editable. |
| Script | A computer script is a list of commands that are executed by a certain program or scripting engine. Scripts may be used to automate processes on a local computer or to generate Web pages on the Web. For example, DOS scripts and VB Scripts may be used to run processes on Windows machines, while AppleScript scripts can automate tasks on Macintosh computers. ASP, JSP, and PHP scripts are often run on Web servers to generate dynamic Web page content. Script files are usually just text documents that contain instructions written in a certain scripting language. This means most scripts can be opened and edited using a basic text editor. However, when opened by the appropriate scripting engine, the commands within the script are executed. VB (Visual Basic) scripts, for example, will run when double-clicked, using Windows' built-in VB scripting support. Since VB scripts can access and modify local files, you should never run a VB script that you receive as an unknown e-mail attachment. |
| Scroll Bar | When the contents of a window are too large to be displayed entirely within the window, a scroll bar will appear. For example, if a Web page is too long to fit within a window, a scroll bar will show up on the right-hand side of the window, allowing you to scroll up and down the page. If the page is too wide for the window, another scroll bar will appear at the bottom of the window, allowing you to scroll to the left and right. If the window's contents fit within the current window size, the scroll bars will not appear. The scroll bar contains a slider that the user can click and drag to scroll through the window. As you may have noticed, the size of the slider may change for different windows. This is because the slider's size represents what percentage of the window's content is currently being displayed within the window. For example, a slider that takes up 75% of the scroll bar means 75% of the content fits within the current window size. A slider that fills only 10% of the scroll bar means only 10% of the window's contents are being displayed within the current window size. Therefore, if two windows are the same size, the one with the smaller slider has more content than the one with the larger slider. Most scroll bars also contain up and down or left and right arrows that allow the user to scroll in small increments by clicking the arrows. However, clicking and dragging the slider is much faster, so the arrow keys are typically not used as often. Also, some mice have a scroll wheel that allows the user to scroll by dragging the wheel instead of clicking and dragging within the scroll bar. |
| Scroll Lock | The scroll lock key is, for most, a way to turn the “scroll lock” light on and off on your keyboard and nothing more. The scroll lock key was intended to function as a third “state” key, such as the Caps Lock and Num Lock keys. Some software makes use of it, but most does not. Some people mock the scroll lock key, but we seek ways to unleash its power! |
| Scroll Wheel | Computer windows are often not large enough to display the entire contents of the window at one time. Therefore, you may need to scroll through the window to view all the contents. Traditionally, this has been done by clicking and dragging the slider within the scroll bar. However, many mice now come with scroll wheels that make the scrolling process even easier. The scroll wheel typically sits between the left and right buttons on the top of a mouse. It is raised slightly, which allows the user to easily drag the wheel up or down using the index finger. Pulling the scroll wheel towards you scrolls down the window, while pushing it away scrolls up. Most modern mice include a scroll wheel, since it eliminates the need to move the cursor to the scroll bar in order to scroll through the window. Therefore, once you get accustomed to using a scroll wheel, it can be pretty difficult to live without. Most scroll wheels only allow the user to scroll up and down. However, some programs allow the user to use a modifier key, such as Control or Shift, to change the scrolling input to left and right. Some mice even have a tilting scroll wheel that allows the user to scroll left and right. The Apple Mighty Mouse has a spherical scrolling mechanism (called a scroll ball) that allows the user to also scroll left and right and even diagonally. Whatever the case, any type of scroll wheel is certainly better than nothing. |
| Scrolling | Most computer programs display their content within a window. However, windows are often not large enough to display their entire content at once. Therefore, you may have to scroll through the window to view the rest of the contents. For example, on some monitors, a page from a word processing document may not fit within the main window when viewed at 100%. Therefore, you may have to scroll down the window to view the rest of the page. Similarly, many Web pages do not fit completely within a window and may require you to scroll both vertically and horizontally to see all the content. To scroll up or down within a window, simply click the scroll bar on the right-hand side of the window and drag the slider up or down. If the window requires horizontal scrolling as well, click the scroll bar at the bottom of the window and drag the slider to the right or left. Some computer mice also include a scroll wheel that allows you to scroll through the window by rolling the wheel back and forth. |
| SCSI | Small Computer Systems Interface. cf IDE. SCSI can be used to interface to any device that has a SCSI interface, this includes devices such as printers and scanners as well as the more traditional disk and tape drives. SCSI adapters typically support one or two SCSI buses, each of which can support up to eight units. Each device on the SCSI bus is identified by a SCSI ID, which ranges from 0 to 7 (or sometimes 0 to 15). The SCSI adapter itself will occupy one of these SCSI IDs leaving 6 (or 14) available for other devices. There are a number of different types of SCSI, reflecting its continuing development, and these are summarised in the following table: SCSI Type Data Width Transfer Rate Max devices Max cable length (metres) SCSI-1 8 bits 5MB/sec 7 6 m (SE) or 12 m (LVD) SCSI-2 Fast (Narrow) 8 bits 10MB/sec 7 3 m (SE) or 12 m (LVD) Fast Wide 16 bits 20MB/sec 15 3 m (SE) or 12 m (LVD) SCSI-3 Ultra (narrow) 8 bits 20MB/sec 7 1.5 m (SE) or 12 m (LVD) Ultra Wide 16 bits 40MB/sec 7 (SE) or 15 (LVD) 1.5m (SE) or 12m (LVD) SCSI-4 Ultra 2 (narrow) 8 bits 40MB/sec 7 12m (LVD) Ultra 2 Wide 16 bits 80MB/sec 15 12m (LVD) Ultra 3 (narrow) 8 bits 80MB/sec 15 12m (LVD) Ultra 3 (wide) 16 bits 160MB/sec 15 12m (LVD) Ultra 320 (wide) 16 bits 320MB/sec 16 12m (LVD) Note: The transfer rate is the maximum throughput of data on the bus, it does not indicate the maximum throughput of a device connected to the bus (for example the bus might be capable of 80MB/sec but a disk drive connected to it might be cable of only a fraction of that.) The maximum cable length (which is the length from the adapter to the last device or terminator) may reduce as devices are added. |
| SCSI-2 | This version of SCSI originally came in two varieties: Fast-SCSI 2 and Fast-Wide SCSI 2. Recent extensions to the SCSI 2 specification include Ultra SCSI and Ultra2 SCSI. Ultra3 SCSI is now called Ultra 160M. |
| SCSI-3 | The SCSI 3 specification doesn’t technically exist, but SCSI-3 is often used to describe the Ultra SCSI standard. Before the time of Ultra SCSI, SCSI-3 was a misnomer for Fast Wide SCSI-2. |
| SD | Stands for "Secure Digital." It is a type of memory card used for storing data in devices such as digital cameras, PDAs, mobile phones, portable music players, and digital voice recorders. The card is one of the smaller memory card formats, measuring 24mm wide by 32mm long and is just 2.1mm thick. To give the cards some orientation, the top-rght corner of each SD card is slanted. Even though the cards are extremely small, as of late 2004, they can hold up to 8GB of data. Part of the reason the cards are called "Secure Digital" cards is because the cards have a copyright protection feature built in. The security feature, called "key revocation" means protected data on the card can only be read by specific devices. The cards can have both secured and unsecured areas on them for copyrighted and non-copyrighted data. |
| SDK | 1. Software Development Kit. 2. Often taken to refer to any of the Microsoft SDKs. |
| SDR | Single Data Rate SDRAM. The first generation SDRAM, which ran at the same speed as the system bus. cf DDR SDRAM, which allows data to be read twice as fast as SDR SDRAM. |
| SDRAM | Synchronous DRAM (Synchronous Dynamic RAM). A type of computer memory which is synchronized with the system clock and runs at the same speed as the system bus. For this reason SDRAM is also sometimes referred to as SDR SDRAM - Single Data Rate SDRAM. cf DDR. |
| SDTV | Standard Definition Television. A television standard providing lower quality images than those provided by HDTV. SDTV includes both the NTSC and PAL television standards. cf HDTV. |
| SDX (Storage Data Acceleration) | This technology was introduced by Western Digital. The idea behind it is that slower drives such as CD and DVD drives would attach directly to larger, faster hard drives. There would be a 10-pin connector between the hard drive and the other peripheral, as opposed to the 40-pin IDE connector. A portion of the hard drive would be used as cache for the CD drive or other device. This was touted to speed up CD-ROM drives by 50%-300% depending on what operations are being performed. You would have had to buy specialized hard drives and CD drives to take advantage of this technology, but it flopped, so don’t worry about it. |
| SEARCH | You can search any individual web page using the CTRL-F command (CMD-F on a Macintosh). Many websites also offer search boxes that let you search all the pages in the site, or records in its database. Searching is usually the most efficient way to find information, but sometimes you can find things by browsing that you might miss otherwise because you might not think of the "right" term to search by. |
| Search Engine | A (usually web-based) system for searching the information available on the Web. Some search engines work by automatically searching the contents of other systems and creating a database of the results. Other search engines contains only material manually approved for inclusion in a database, and some combine the two approaches. See also: WWW |
| Seat (v. to seat, or n. seat) | The installation of memory or other accessories into a computer. It can also be used as a noun to describe a single license, or a single client workstation for licensing purposes. |
| Sector | A sector is the smallest unit that can be accessed on a hard disk. Each platter, or circular disk of a hard disk is divided into tracks, which run around the disk. These tracks get longer as they move from the middle towards the outside of the disk, so there are more sectors along the tracks near the outside of the disk than the ones towards the center of disk. This variance in sectors per track is referred to as "zoned-bit recording." Large files can take up thousands of sectors on a disk. Even if one of these sectors becomes corrupted, the file will most likely be unreadable. While a disk utility program may be able to fix corrupted data, it cannot fix physical damage. Physically damaged sectors are called "bad sectors." While your computer may recognize and bypass bad sectors on your hard disk, certain bad sectors may prevent your disk from operating properly. Yet another good reason to always back up your data! |
| Secure Electronic Transactions (SET) | Secure Electronic Transactions is a protocol developed for credit card transactions in which all parties (customers, merchant, and bank) are authenticated using digital signatures, encryption protects the message and provides integrity, and provides end-to-end security for credit card transactions online. |
| Secure HyperText Transfer Protocol (HTTPS) | A secure means of transferring data using the HTTP protocol. Typically HTTP data is sent over TCP/IP port 80, but HTTPS data is sent over port 443. This standard was developed by Netscape for secure transactions, and uses 40-bit encryption (”weak” encryption) or 128-bit (”strong” encryption). If you are at a secure site, you will notice that there is a closed lock icon on the bottom area of your Navigator or IE browser. The HTTPS standard supports certificates. A webserver operator must get a digital certificate from a third-party certificate provider that ensures that the webserver in question is valid. This certificate gets installed on the webserver, and verifies for a period of a year that that server is a proper secure server. |
| Secure Shell (SSH) | A program to log into another computer over a network, to execute commands in a remote machine, and to move files from one machine to another. |
| Secure Sockets Layer (SSL) | A protocol specified by Netscape that allows for “secure” passage of data. It uses public key encryption, including digital certificates and digital signatures, to pass data between a browser and a server. It is an open standard and is supported by most modern browsers. |
| Security Certificate | A chunk of information (often stored as a text file) that is used by the SSL protocol to establish a secure connection. |
| Security Policy | A set of rules and practices that specify or regulate how a system or organization provides security services to protect sensitive and critical system resources. |
| Segment | Segment is another name for TCP packets. |
| Self-Monitoring Analysis and Reporting Tool (SMART) | This technology reports on a variety of hard drive attributes. You need a compliant BIOS and SCSI and/or IDE controller, a hard drive that supports SMART, and some sort of software package that reports on these conditions. Once you have that you should be able to receive system warnings about your hard drive. Many hard drive manufacturers have added onto the SMART technology or changed it around so that it has proprietary features for their drives. The good news about SMART is that having SMART is much better than not having it, and you can be warned of hard drive failure before it happens and backup your drive while it still works. Thus, your data is safer with SMART around. |
| Semiconductor | A substance (usually silicon doped with germanium or arsenic) that selectively conducts electricity. The selection usually occurs by running another current through a different axis to turn current flow on or off. Microprocessors are made of semiconductive materials. |
| Separation of Duties | Separation of duties is the principle of splitting privileges among multiple individuals or systems. |
| Serial | A means of operation meaning in series, or one after the other. It refers to connection standards that use a single wire. See also parallel. |
| Serial ATA | Serial ATA is a disk-interface technology developed by a group of the industry's leading vendors to replace parallel ATA. It is the natural successor to IDE. Serial ATA only requires seven wires per device (4 data and 3 ground) and the cables can be up to 1m long. SATA I (the first version of SATA) supports data transfer speeds of up to 150mbps. SATA II supports data transfer speeds of up to 300mbps. Whilst the SATA interface supports these transfer rates it does not mean that the disk drive is capable of reading/writing at that rate. SATA also supports hot-swap of devices. |
| Serial Port | A data port/connection standard that is usually used to connect modems and mice. It comes in 9- and 25-pin varieties, both of which effectively function the same way. Serial ports are largely being eliminated in favor of much faster USB and FireWire connection standards. |
| Server | A computer, or a software package, that provides a specific kind of service to client software running on other computers. The term can refer to a particular piece of software, such as a WWW server, or to the machine on which the software is running, e.g. "Our mail server is down today, that's why e-mail isn't getting out." A single server machine can (and often does) have several different server software packages running on it, thus providing many different servers to clients on the network. Sometimes server software is designed so that additional capabilities can be added to the main program by adding small programs known as servlets. |
| Server Consolidation | The operation of mitigating the so called server sprawl by optimizing resource usage and simplifying management of available computers. Consolidation can be logical (managing distributed computers with central management) physical (moving several computers in a central location) or rationalized (migrate several computers in virtual machines or partitions, hosted by a single physical computer). |
| Server Farm | A group of servers usually located in a secure area, and sometimes collocated at an ISP. These servers all serve a single purpose (such as serving Web pages, for example) and have some sort of load balanced across them. If one server in the farm dies, business carries on as usual. If performance is slow, you add more servers. This term is popular when dealing with Web-based applications, where a group of webservers all serve up the same content or pull data from a database server or group of database servers. |
| Server Sprawl | The irrational proliferation of multiple computers inside a company infrastructure. |
| SERVER-SIDE | Something that operates on the "server" computer (providing the Web page), as opposed to the "client" computer (which is you or someone else viewing the Web page). Usually it is a program or command or procedure or other application causes dynamic pages or animation or other interaction. |
| Servlet | A small computer program designed to be add capabilities to a larger piece of server software. Common examples are "Java servlets", which are small programs written in the Java language and which are added to a web server. Typically a web server that uses Java servlets will have many of them, each one designed to handle a very specific situation, for example one servlet will handle adding items to a "shopping cart", while a different servlet will handle deleting items from the "shopping cart." |
| Session | A session is a virtual connection between two hosts by which network traffic is passed. |
| Session Hijacking | Take over a session that someone else has established. |
| Session Key | In the context of symmetric encryption, a key that is temporary or is used for a relatively short period of time. Usually, a session key is used for a defined period of communication between two computers, such as for the duration of a single connection or transaction set, or the key is used in an application that protects relatively large amounts of data and, therefore, needs to be re-keyed frequently. |
| SFF | Small Form Factor. Small Form Factor refers to a small sized case for a PC, much smaller than a standard ATX tower or mini/midi tower case. Whilst there does not appear to be a strict definition of what constitutes a small form factor case, it would normally occupy a footprint not much larger than that of the motherboard it contains (which are often but not always standard ATX motherboards), but would be high enough to accommodate some expansion cards (normally no more than two), as well as power supply and disk drives. SFF has the advantage that it occupies much less space than a standard PC, but has the disadvantage that the lack of internal space means there are fewer upgrade options. |
| SFTP | 1. Secure FTP (File Transfer Protocol). Also known as "SSH File Transfer Protocol". A network protocol providing file transfer and manipulation over a secure data stream. 2. FTP over SSH. Running FTP over a secure SSH connection. 3. Simple File Transfer Protocol. A protocol (defined by RFC 913) for an unsecured file transfer protocol that was less complicated and easier to implement than FTP. SFTP was not widely adopted and is generally regarded as obsolete. |
| SHA1 | A one way cryptographic hash function. Also see "MD5" |
| Shadow Password Files | A system file in which encryption user password are stored so that they aren't available to people who try to break into the system. |
| Share | A share is a resource made public on a machine, such as a directory (file share) or printer (printer share). |
| Shareware | Software that is distributed on a try-before-you-buy basis. Typically you are allowed to use the software for a period of 30 days before needing to purchase a license, but terms and conditions will vary. Strictly shareware is a marketing method rather than a type of software, but the name is normally applied to software which is distributed and sold under the heading of shareware. |
| Shell | Most people know of shells as small protective coverings for certain animals, such as clams, crabs, and mollusks. You may also find a shell on the outside of an egg, which I highly recommend you remove before eating. In the computer science world, however, a shell is a software program that interprets commands from the user so that the operating system can understand them and perform the appropriate functions. The shell is a command-line interface, which means it is soley text-based. The user can type commands to perform functions such as run programs, open and browse directories, and view processes that are currently running. Since the shell is only one layer above the operating system, you can perform operations that are not always possible using the graphical user interface (GUI). Some examples include moving files within the system folder and deleting files that are typically locked. The catch is, you need to know the correct syntax when typing the commands and you may still be prompted for a password in order to perform administrative functions. Shells are most commonly associated with Unix, as many Unix users like to interact with the operating system using the text-based interface. Two common Unix shells are the Bourne shell and the C Shell, which is used by BSD. Most Unix systems have both of these shells available to the user. Windows users may be more familiar with DOS, the shell that has long been included with the Windows operating system. Most computer users have no need to use the shell interface, but it can be a fun way to perform functions on your computer, as well as impress your friends. |
| Shell Account | A term used with Internet dial-up accounts that can access a UNIX system at the command line instead of just connecting to the Internet through a browser. Shell accounts were at one time offered by many ISPs, but have fallen out of favor as the larger ISPs now cater mainly to volume users instead of more technical users. |
| Shift Key | Shift is a modifier key that allows you to capitalize lowercase letters and enter various symbols and punctuation marks. To use the Shift key, simply press and hold Shift while typing another key on the keyboard. The Shift key can be used in conjunction with the Command (Mac) or Control (PC) keys to perform various keyboard shortcuts. Many programs also allow the Shift key to be used with the mouse button in order to select multiple objects. For example, to select more than one object, click on the first object, then hold the Shift key while clicking on the other objects you want to select. |
| Shockwave | A technology that enables web pages to include multimedia objects such as audio, animation, and video; you use an authoring tool by Macromedia called "Director" to create a shockwave object and a program called "Afterburner" to compress the object. A plug-in available from Macromedia's web site is required to see a Shockwave object included on a web page. |
| Shortcut | A file on Windows system that serves as a pointer to another file or folder. Shortcuts are similar in concept to a symbolic link on Unix systems, but are not as versatile - for instance a shortcut cannot be used by scripts. |
| SHTTP | Secure Hypertext Transmission Protocol (Secure-HTTP). An extended version of HTTP providing security through encryption. SHTTP encrypts data transfers, but does not authenticate the client. The responsibility for authentication remains with the website (i.e. the responsibility for determining whether the visitor should be shown the information in the first place). cf HTTPS. |
| SID | Security Identifier, or Security ID. A SID uniquely identifier a user, group or computer. |
| Signals Analysis | Gaining indirect knowledge of communicated data by monitoring and analyzing a signal that is emitted by a system and that contains the data but is not intended to communicate the data. |
| Signature | 1. A file containing a bit of personal information that you can set to be automatically appended to your outgoing e-mail messages; many network newsreaders also have this capability. Large signatures over five lines generally are frowned upon. 2. A Signature is a distinct pattern in network traffic that can be identified to a specific tool or exploit. |
| SIMM | Stands for "Single In-Line Memory Module." This is an older type of computer memory. A SIMM is a small circuit board with a bunch of memory chips on it. SIMMs use a 32-bit bus, which is not as wide as the 64-bit bus dual in-line memory modules (DIMMs) use. Newer processors require a 64-bit memory bus, so it is best to use DIMMs. Sometimes you can get away with installing SIMMS, but they have to be installed in pairs. |
| Simple Integrity Property | In Simple Integrity Property a user cannot write data to a higher integrity level than their own. |
| SIP | 1. Session Initiation Protocol. Used for setting up communications sessions on the internet, such as instant messaging, conferencing, telephony or whiteboarding. 2. Single in-line package. |
| Site Map | A site map, sometimes written "sitemap," is an overview of the pages within a website. Site maps of smaller sites may include every page of the website, while site maps of larger sites often only include pages for major categories and subcategories of the website. While site maps can be organized in a variety of ways, most use an outline form, with pages arranged by topic. This gives visitors a good overall picture of how the site is organized and clearly defines all the resources the website has to offer. While a properly designed website should allow visitors to navigate the entire site without using the site map, incorporating a site map gives users another means of locating pages. For this reason, each page listed in a site map is typically linked to the page it represents. This allows visitors to quickly jump to any section of a website listed in the site map. |
| SKU (Stock Keeping Unit) | Stands for "Stock Keeping Unit," and is conveniently pronounced "skew." A SKU is a number or string of alpha and numeric characters that uniquely identify a product. For this reason, SKUs are often called part numbers, product numbers, and product identifiers. SKUs may be a universal number such as a UPC code or supplier part number or may be a unique identifier used by a specific a store or online retailer. For example, one company may use the 10 character identifier supplied by the manufacturer as the SKU of an external hard drive. Another company may use a proprietary 6-digit number as the SKU to identify the part. Many retailers use their own SKU numbers to label products so they can track their inventory using their own custom database system. When shopping online or at retail stores, knowing a product's SKU can help you locate the exact product at a later time. It will help you identify a unique product when there are many similar options, such as a TV model that comes in different colors, sizes, etc. If you know a product's SKU, you can typically locate the product online by typing the SKU in the online retailer's search box. If you visit a retail store and have questions about product you saw in an ad, knowing the SKU will help the salesperson find the exact product you are asking about. SKUs are typically listed in small print below the product name and are often preceded by the words "SKU," "Part Number," "Product ID," or something similar. |
| SLA (Service Level Agreement) | An agreement between a service provider and a customer regulating offered service in several aspects, from amount of resources available to time availability, up to faults recovery timeframe. |
| Slashdot Effect | This describes what happens when a highly trafficked website links to a smaller website, and sends such a large amount of traffic towards the smaller website over a short period of time that the website becomes inaccessible, or at least very slow. The phrase was first used to describe the effect that Slashdot.org had when it linked to small sites in its daily news items. |
| Slave | This usually refers to an IDE setting on a hard drive or other IDE device. When two devices are used on a single IDE channel, one is set to master and the other to slave. See also master. |
| Sleep mode | The placement of a computing device into an inoperable mode, where less power is consumed by shutting down unnecessary devices, but leaving all data in RAM. Typically you return from sleep mode by using the keyboard or mouse, and devices are switched back on. Sleep mode in its early incarnations was very problematic in some PCs, and would often crash programs and operating systems that were not completely compatible with the sleep mode in the PC’s BIOS. |
| SMART | 1. Self Monitoring Analysis and Reporting Technology. A HDD diagnostic technology that monitors device performance and attempts to predict device failure. SMART software on the HDD monitors the internal performance of motors, media, heads and electronics of the drive. SMART software on the host monitors the overall reliability status of the drive. |
| SMART (Self-Monitoring Analysis and Reporting Tool) | This technology reports on a variety of hard drive attributes. You need a compliant BIOS and SCSI and/or IDE controller, a hard drive that supports SMART, and some sort of software package that reports on these conditions. Once you have that you should be able to receive system warnings about your hard drive. Many hard drive manufacturers have added onto the SMART technology or changed it around so that it has proprietary features for their drives. The good news about SMART is that having SMART is much better than not having it, and you can be warned of hard drive failure before it happens and backup your drive while it still works. Thus, your data is safer with SMART around. |
| Smartcard | A smartcard is an electronic badge that includes a magnetic strip or chip that can record and replay a set key. |
| SmartMedia | A type of Flash memory card that is roughly one-third the size of a PC Card (PCMCIA card) and less than 1 mm thick. It is used to store data from and exchange data among PDAs, digital cameras, and other devices. SmartMedia has largely given way to the even smaller MMC MultiMedia Card standard. |
| SMB | Server Message Block. File sharing protocol used in DOS, OS/2 and early versions of Windows. |
| SMS | 1. Short Message Service - mobile phone text messaging. 2. (Microsoft) Systems Management Server. |
| SMT | 1. Simultaneous Multithreading Technology. See also: Hyper-Threading. 2. Surface Mount Technology. A manufacturing technique where components are design for direct mounting on the surface of a PC board or substrate. 3. Senior Management Team. Typically used to refer to heads of department in a company which direct company policy. |
| SMTP | Simple Mail Transfer Protocol. A protocol for sending (or relaying) e-mail to a server. See also: IMAP, POP, MX Record. |
| Smurf | The Smurf attack works by spoofing the target address and sending a ping to the broadcast address for a remote network, which results in a large amount of ping replies being sent to the target. |
| Smurf Attack | A network-based attack where the attacker(s) send out false ICMP echo requests that appear to originate from the IP address of the machine or network under attack. This type of attack can be used to flood a network or device with “responses” to the false ICMP requests. |
| Snail Mail | A derogatory term for the traditional postal mail service, where physical items (typically letters) are posted, transported and delivered to their destination. It is called snail mail only when being compared email, because it is very slow in comparison. |
| Snapshot | While the term "snapshot" is often used in photography, it is also a computing term that refers to a copy made of a disk drive at a specific moment in time. Snapshots are useful for backing up data at different intervals, which allows information to be recovered from different periods of time. A hard drive snapshot includes the full directory structure of a hard disk, including all folders and files on the disk. This type of backup may also be referred to as a "disk image." Disk images allow the full disk to be restored in case the primary disk fails. Many backup programs that create snapshots also allow specific files to be recovered from the snapshot, instead of having to restore the complete backup. Since snapshots are mainly used for backup purposes, it is wise to save the snapshot to a secondary hard drive, removable drive, or optical media, such as CDs or DVDs. |
| Sniffer | A sniffer is a tool that monitors network traffic as it received in a network interface. |
| Sniffing | A synonym for "passive wiretapping." |
| SNMP | A set of standards for communication with devices connected to a TCP/IP network. Examples of these devices include routers, hubs, and switches. SNMP is defined in RFC 1089 See also: Network, RFC, Router, TCP/IP |
| SNTP | Simple Network Time Protocol. |
| SOAP | Simple Object Access Protocol. A protocol that describes a model for packing XML enquiries and responses. SOAP messaging is used to enable exchange of a variety of XML information. The SOAP standard takes on the job of transporting service requests and replies between service users and service providers. SOAP is a way to encapsulate object calls to XML sent via HTTP. |
| Social Engineering | A euphemism for non-technical or low-technology means - such as lies, impersonation, tricks, bribes, blackmail, and threats - used to attack information systems. |
| Socket | 1. An IP address and port number. Applications communicate by sockets - the ip address indicates the network address of the machine to which messages should be sent and the port number is the logical destination on that machine. 2. A receptacle into which a component can be fitted. The socket is the female component of any plug and socket arrangement. For example on the motherboard of a computer the CPU will be fitted into a matching socket (which may sometimes take the form of a slot), or for with a portable CD player the headphones will plug into the headphone socket. |
| Socket Pair | A way to uniquely specify a connection, i.e., source IP address, source port, destination IP address, destination port. |
| SOCKS | A protocol that a proxy server can use to accept requests from client users in a company's network so that it can forward them across the Internet. SOCKS uses sockets to represent and keep track of individual connections. The client side of SOCKS is built into certain Web browsers and the server side can be added to a proxy server. |
| Soft Copy | soft copy is a document saved on a computer. It is the electronic version of a document, which can be opened and edited using a software program. The term "soft copy" is most often used in contrast to hard copy, which is the printed version of a document. Soft copies can be sent via e-mail or over a network connection, which makes them a more efficient and cost effective option than using hard copies for communications. The downside to using soft copies is that they require a computer and software to open and can be accidentally deleted. Of course, some people have so many papers on their desks, a soft copy may be less likely to disappear. |
| Soft Token | A soft token is a software version of a hard token, which is a security device used to give authorized users access to secure locations or computer systems. For this reason, soft tokens can be called "virtual tokens," since they are a virtual version of hardware keys and other physical security devices. Soft tokens are typically generated by a central server that runs security software. They are sent to users' devices, such as cell phones, PDAs, and laptops. Once the soft token has been received by the device, the user can use the device within a secure network or can gain access to the sever as an authorized user. To add an extra measure of security, most soft token authentication also requires a username and password to make sure the correct user is using the authorized device. |
| Software | Computer software is a general term that describes computer programs. Related terms such as software programs, applications, scripts, and instruction sets all fall under the category of computer software. Therefore, installing new programs or applications on your computer is synonymous with installing new software on your computer. Software can be difficult to describe because it is "virtual," or not physical like computer hardware. Instead, software consists of lines of code written by computer programmers that have been compiled into a computer program. Software programs are stored as binary data that is copied to a computer's hard drive, when it is installed. Since software is virtual and does not take up any physical space, it is much easier (and often cheaper) to upgrade than computer hardware. While at its most basic level, software consists of binary data, CD-ROMs, DVDs, and other types of media that are used to distribute software can also be called software. Therefore, when you buy a software program, it often comes on a disc, which is a physical means of storing the software. |
| Software bug | A software bug is the common term used to describe an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways. Most bugs arise from mistakes and errors made by people in either a program's source code or its design, and a few are caused by compilers producing incorrect code. A program that contains a large number of bugs, and/or bugs that seriously interfere with its functionality, is said to be buggy. Reports detailing bugs in a program are commonly known as bug reports, fault reports, problem reports, trouble reports, change requests, and so forth. Effects Main article: List of software bugs Bugs trigger Type I and type II errors that can in turn have a wide variety of ripple effects, with varying levels of inconvenience to the user of the program. Some bugs have only a subtle effect on the program's functionality, and may thus lie undetected for a long time. More serious bugs may cause the program to crash or freeze leading to a denial of service. Others qualify as security bugs and might for example enable a malicious user to bypass access controls in order to obtain unauthorized privileges. The results of bugs may be extremely serious. Bugs in the code controlling the Therac-25 radiation therapy machine were directly responsible for some patient deaths in the 1980s. In 1996, the European Space Agency's US$1 billion prototype Ariane 5 rocket was destroyed less than a minute after launch, due to a bug in the on-board guidance computer program. In June 1994, a Royal Air Force Chinook crashed into the Mull of Kintyre, killing 29. This was initially dismissed as pilot error, but an investigation by Computer Weekly uncovered sufficient evidence to convince a House of Lords inquiry that it may have been caused by a software bug in the aircraft's engine control computer. [1] In 2002, a study commissioned by the US Department of Commerce' National Institute of Standards and Technology concluded that software bugs, or errors, are so prevalent and so detrimental that they cost the US economy an estimated $59 billion annually, or about 0.6 percent of the gross domestic product. |
| Solaris | A UNIX-based operating system developed by Sun Microsystems and used widely for enterprise-class servers. It is designed to work with Sun’s own SPARC chips as well as Intel’s x86 microprocessors. |
| Solid State | Solid state, at its most basic level, means "no moving parts." Therefore, solid state electronic devices are made up of solid components that do not move. Some examples include computer motherboards and integrated circuits. Devices that use only solid state parts, such as television sets, speakers, and digital watches, are often referred to as solid state products. Flash memory devices are solid state products, while hard drives are not. This is because hard drives use a spinning disk and moving drive head to read and write data, while flash memory uses electric charges to perform the same functions. For this reason, flash memory devices are seen as more durable than hard drives. This is why flash memory is often used in products such as portable MP3 players and digital cameras. Because solid state devices have no moving parts, they are less likely to break down than devices that have mobile mechanisms. For this reason, it is often more worthwhile to buy an extended warranty on electronics that have moving parts than those that do not. That is something you may want to think about next time you are shopping. |
| Sound Card | The sound card is a component inside the computer that provides audio input and output capabilities. Most sound cards have at least one analog line input and one stereo line output connection. The connectors are typically 3.5 mm minijacks, which are the size most headphones use. Some sound cards also support digital audio input and output, either through a standard TRS (tip-ring-sleeve) connection or via an optical audio port, such as Toslink connector. While there are many types of sound cards, any type that produces an analog output must include a digital-to-analog converter (DAC). This converts the outgoing signal from digital to analog, which can be played through most speaker systems. Sounds cards that support analog input also require an analog-to-digital converter (ADC). This digitizes the incoming analog signal, so the computer can process it. In some computers, the sound card is part of the motherboard, while other machines may have an actual card that reside in a PCI slot. If you want to more audio capabilities to your computer, such as additional input or output channels, you can install a new sound card. Professional sound cards often support higher sampling rates (such as 192 kHz instead of 44.1 kHz) and may have more inputs and outputs. Some cards may also have 1/4 in. connectors instead of 3.5 mm, which accommodates most instrument outputs. While professional sound cards can add more audio capabilities to your computer, another popular option for multi-channel recording is a breakout box. This is an external box that typically includes a built-in sound card and multiple audio connections. For example, a breakout box may support 16 channels of audio, which would be impossible to fit on a single card. Most breakout boxes connect to a Firewire or USB port, though some connect to a sound card specifically designed to communicate with the box. |
| Source Code | Every computer program is written in a programming language, such as Java, C/C++, or Perl. These programs include anywhere from a few lines to millions of lines of text, called source code. Source code, often referred to as simply the "source" of a program, contains variable declarations, instructions, functions, loops, and other statements that tell the program how to function. Programmers may also add comments to their source code that explain sections of the code. These comments help other programmers gain at least some idea of what the source code does without requiring hours to decipher it. Comments can be helpful to the original programmer as well if many months or years have gone by since the code was written. Short programs called scripts can be run directly from the source code using a scripting engine, such as a VBScript or PHP engine. Most large programs, however, require that the source code first be compiled, which translates the code into a language the computer can understand. When changes are made to the source code of these programs, they must be recomplied in order for the changes to take effect in the program. Small programs may use only one source code file, while larger programs may reference hundreds or even thousands of files. Having multiple source files helps organize the program into different sections. Having one file that contains every variable and function can make it difficult to locate specific sections of the code. Regardless of how many source code files are used to create a program, you will most likely not see any of the original files on your computer. This is because they are all combined into one program file, or application, when they are compiled. |
| Source Port | The port that a host uses to connect to a server. It is usually a number greater than or equal to 1024. It is randomly generated and is different each time a connection is made. |
| Southbridge | The southbridge is a chip that connects the northbridge to other components inside the computer, including hard drives, network connections, USB and Firewire devices, the system clock, and standard PCI cards. The southbridge sends and receives data from the CPU through the northbridge chip, which is connected directly to the computer's processor. Since the southbridge is not connected directly to the CPU, it does not have to run as fast as the northbridge chip. However, it processes data from more components, so it must be able to multitask well. On Intel systems, the southbridge is also referred to as the I/O Controller Hub, since it controls the input and output devices. |
| SP1 | Service Pack 1. The first service pack (SP) released for a given product. Not all products will have service packs released for them. The existence of SP1 does not imply the existence of SP2 for the same produce. |
| SP2 | Service Pack 2. The second service pack (SP) for a given product. Depending on the service pack, SP2 may require SP1 to have been pre-installed or (more likely) it may include everything contained in SP1. |
| SP3 | Service Pack 3. |
| SPAM | 1. Unsolicited e-mail (or newsgroup posting) sent out in bulk, usually for commercial gain. SPAM is typically promoting something. It may be advertising for a product, website or other service, it may be promoting ideologies (such as political or religious ones), or it may be to precipitate a fraud. Whist most SPAM is sent out for purposes of commercial gain, not all is spam has a financial motive. SPAM can cause considerable problems because it is generated in large volume - both the volume generated by a single spammer and because there are lots of spammers generating email. The large volume of spam clogs up network resources and wastes a considerable amount of time. |
| Spam (v. to spam, n. spam) | Besides being a canned meat (”spiced ham” made by Hormel) spam has taken on a new meaning. Spam is the common term for unsolicited e-mail. Some common types of spam include ads for pornographic sites, pyramid schemes, and advertisements for products that allow you to send spam. Other types of spam are messages that claim that you will win a prize or help a dying child by sending messages to all of your friends. In addition to being a noun, spam is also a verb, as in “Don’t spam me!” Often spammers will take the list of addresses that reply to them asking them to stop sending their messages, and will then compile new lists to spam further. |
| Spammer | A person or organisation that sends out spam. Spammers tend to go to extreme lengths to hide their identity because they are generally despised and hated by the internet community because spam is unwanted, clogs up network resources and wastes a considerable amount of time. |
| Spanning Port | Configures the switch to behave like a hub for a specific port. |
| SpeedStep | SpeedStep is a trademark for a series of dynamic frequency scaling technologies (including SpeedStep, SpeedStep II, and SpeedStep III) built into some Intel microprocessors that allow the clock speed of the processor to be dynamically changed by software. This allows the processor to meet the instantaneous performance needs of the operation being performed, while minimizing power draw and heat dissipation. Explanation Running a processor at high clock speeds allows for better performance. However, when the same processor is run at a lower frequency (speed), it generates less heat and consumes less power. In many cases, the core voltage can also be reduced, further reducing power consumption and heat generation. This can conserve battery power in notebooks, extend processor life, and reduce noise generated by variable-speed fans. By using SpeedStep, users can select the balance of power conservation and performance that best suits them, or even change the clock speed dynamically as the processor burden changes. |
| SPF | Sender Policy Framework. SPF records indicate which mail servers are permitted to send email with a given "from" address. SPF is an attempt to counter "e-mail address spoofing", where a sender (typically a spammer) uses someone else's e-mail address as the apparent sender of an e-mail. |
| SPI | Stateful Packet Inspection. A firewall mechanism which examines each incoming network packet and only allows through those packets which are for a known open connection. |
| Spider | A spider is a software program that travels the Web (hence the name "spider"), locating and indexing websites for search engines. All the major search engines, such as Google and Yahoo!, use spiders to build and update their indexes. These programs constantly browse the Web, traveling from one hyperlink to another. For example, when a spider visits a website's home page, there may be 30 links on the page. The spider will follow each of the links, adding all the pages it finds to the search engine's index. Of course, the new pages that the spider finds may also have links, which the spider continues to follow. Some of these links may point to pages within the same website (internal links), while others may lead to different sites (external links). The external links will cause the spider to jump to new sites, indexing even more pages. Because of the interwoven nature of website links, spiders often return to websites that have already been indexed. This allows search engines to keep track of how many external pages link to each page. Usually, the more incoming links a page has, the higher it will be ranked in search engine results. Spiders not only find new pages and keep track of links, they also track changes to each page, helping search engine indexes stay up to date. |
| Spindle | The centerpiece of a hard drive which holds one or more hard drive platters. Often the term spindle is used to differentiate hard drives from hard disk platters in discussion when referring to large RAID subsystems holding many hard drives, such as “We’ll be using 50 spindles instead of 10 spindles in the new RAID box.” Basically a spindle is seen as a limiting factor in performance; generally, more spindles in a system mean higher possible performance. |
| Split Horizon | Split horizon is a algorithm for avoiding problems caused by including routes in updates sent to the gateway from which they were learned. |
| Split Key | A cryptographic key that is divided into two or more separate data items that individually convey no knowledge of the whole key that results from combining the items. |
| SPONSOR (of a Web page or site) | Many Web pages have organizations, businesses, institutions like universities or nonprofit foundations, or other interests which "sponsor" the page. Frequently you can find a link titled "Sponsors" or an "About us" link explaining who or what (if anyone) is sponsoring the page. Sometimes the advertisers on the page (banner ads, links, buttons to sites that sell or promote something) are "sponsors." WHY is this important? Sponsors and the funding they provide may, or may not, influence what can be said on the page or site -- can bias what you find, by excluding some opposing viewpoint or causing some other imbalanced information. The site is not bad because of sponsors, but you they should alert you to the need to evaluate a page or site very carefully. |
| Spoof | A generic term for misleading a computer system into believing that you are not who you say you are. Most commonly, it refers to a TCP/IP trick that allows you to get around network security by impersonating a TCP/IP address inside of the network. |
| Spoofing | The word "spoof" means to hoax, trick, or deceive. Therefore, in the IT world, spoofing refers tricking or deceiving computer systems or other computer users. This is typically done by hiding one's identity or faking the identity of another user on the Internet. Spoofing can take place on the Internet in several different ways. One common method is through e-mail. E-mail spoofing involves sending messages from a bogus e-mail address or faking the e-mail address of another user. Fortunately, most e-mail servers have security features that prevent unauthorized users from sending messages. However, spammers often send spam messages from their own SMTP, which allows them to use fake e-mail addresses. Therefore, it is possible to receive e-mail from an address that is not the actual address of the person sending the message. Another way spoofing takes place on the Internet is via IP spoofing. This involves masking the IP address of a certain computer system. By hiding or faking a computer's IP address, it is difficult for other systems to determine where the computer is transmitting data from. Because IP spoofing makes it difficult to track the source of a transmission, it is often used in denial-of-service attacks that overload a server. This may cause the server to either crash or become unresponsive to legitimate requests. Fortunately, software security systems have been developed that can identify denial-of-service attacks and block their transmissions. Finally, spoofing can be done by simply faking an identity, such as an online username. For example, when posting on an Web discussion board, a user may pretend he is the representative for a certain company, when he actually has no association with the organization. In online chat rooms, users may fake their age, gender, and location. While the Internet is a great place to communicate with others, it can also be an easy place to fake an identity. Therefore, always make sure you know who you are communicating with before giving out private information. |
| Spool | A spool is a temporary storage area within the computer's RAM that contains input or output data. When a job or process is initiated on a computer, but cannot be run immediately, it is often placed in a spool. This process is called spooling. The spool holds the data until the appropriate device is ready to use it. The most common type of spool is a print spool, which stores print jobs that are sent to a printer. Since the printer may need to warm up before printing a document, the document may be held in the spool during the printer's warm up process. If there are multiple documents that have been sent to the printer, the print spool may contain a queue of jobs. You can think of a print spool as a spool of yarn that is connected from the computer to the printer. Of course, the print spool contains computer data, rather than yarn. As the the data is transmitted to the printer, it is removed from the computer, just like unraveling a spool. Once the spool is empty, no more data is transmitted to the printer. |
| Spooling | Sending a print job to a print queue, from where it is sent to a printer, rather than directly to the printer. |
| spread spectrum | Spread spectrum is a type of modulation that scatters data transmissions across the available frequency band in a pseudorandom pattern. Spreading the data across the frequency spectrum makes the signal resistant to noise, interference, and snooping. Spread-spectrum modulation schemes are commonly used with personal communication devices such as digital cellular phones, as well as with wireless local area networks (LANs) and cable modems. |
| Spreadsheet | A spreadsheet is a document that stores data in a grid of horizontal rows and vertical columns. Rows are typically labeled using numbers (1, 2, 3, etc.), while columns are labeled with letters (A, B, C, etc). Individual row/column locations, such as C3 or B12, are referred to as cells. Each cell can each store a unique instance of data. By entering data into a spreadsheet, information can be stored in a more structured way than using plain text The row/column structure also allows the data to be analyzed using formulas and calculations. For example, each row of a spreadsheet may store information about a person who has an account with a certain company. Each column may store a different aspect of the person's information, such as the first name, last name, address, phone number, favorite food, etc. The spreadsheet program can analyze this data by counting the number of people who live in a certain zip code, listing all the people who's favorite food is fried veal, or performing other calcuations. In this way, a spreadsheet is similar to a database. However, spreadsheets are more streamlined than databases and are especially useful for processing numbers. This is why spreadsheets are commonly used in scientific and financial applications. For example, a spreadsheet may store bank account data, including balance and interest information. A column that stores the account balances of several clients can easily be summed to produce the total value of all the clients' balances. These amounts can be multiplied by the interest rate from another cell to see what the value of the accounts will be in a year. Once the formula has been created, modifying the value of just the interest rate cell will also change the projected value of all the accounts. The most commonly used spreadsheet application is Microsoft Excel, but several other spreadsheet programs are available including IBM Lotus 1-2-3 for Windows and AppleWorks and Numbers for Mac OS X. |
| SPS | Stand-by Power Supply. A cheaper form of UPS (see UPS for comparison). |
| Spyware | Spyware Software that monitors the activities of a user (such as their browsing habits) or gathers information about a user (such as stored credit card details) without the user's knowledge or permission. This information is collected so that it can be relayed to a third party. Spyware is typically used as a prelude to theft or fraud. Once credit card or personal information has been collected and relayed to a third party that third party is able to use the information to commit a theft or fraud. |
| SQL | Structured Query Language. Standard query language is a standard language available on virtually all database systems for quering, adding and updating information from database systems |
| SQL Injection | An attack technique where an attacker tries to make an application execute unauthorised (or unintended) SQL. |
| SRAM | Stands for "Static Random Access Memory." I know it is tempting to pronounce this term as "Sram," but it is correctly pronounced "S-ram." SRAM is a type of RAM that stores data using a static method, in which the data remains constant as long as electric power is supplied to the memory chip. This is different than DRAM (dynamic RAM), which stores data dynamically and constantly needs to refresh the data stored in the memory. Because SRAM stores data statically, it is faster and requires less power than DRAM. However, SRAM is more expensive to manufacture than DRAM because it is built using a more complex structure. This complexity also limits the amount of data a single chip can store, meaning SRAM chips cannot hold as much data as DRAM chips. For this reason, DRAM is most often used as the main memory for personal computers. However, SRAM is commonly used in smaller applications, such as CPU cache memory and hard drive buffers. It is also used in other consumer electronics, from large appliances to small children's toys. It is important to not confuse SRAM with SDRAM, which is a type of DRAM. |
| sRGB | Stands for "Standard RGB" (and RGB stands for Red-Green-Blue"). All the colors you see on your computer display are made up various mixtures of red, green, and blue light. While this works great for individual displays, the same colors are often displayed differently on different screens. For example, dark red on one screen may look like red-orange on another. When you add printers, scanners, and digital cameras to the mix, the problem is magnified even more. To help achieve a greater color consistency between hardware devices, the sRGB standard was created in 1999. It defines a gamut of colors that represents each color well and can be used by CRT monitors, LCD screens, scanners, printers, and digital cameras. It also has been incorporated into many Web browsers to make sure the colors on Web pages match the color scheme of the operating system. Because of the color consistency sRGB creates, most hardware devices that work with images now use it as the default setting. |
| SSD | Solid State Drive. A disk drive technology which stores data to solid state devices (flash) without the need for any moving parts. |
| SSD (Solid State Drive) | This type of storage is basically a huge block of RAM chips that functions like a hard drive. Solid state drives are extremely expensive, but offer very high data speeds that are necessary in some applications. They can also be used as large caches on huge RAID subsystems, but due to the volatile nature of the DRAM used as storage solid state drives should be used carefully. |
| SSH | Secure Shell. A set of applications and protocols to provide secure encrypted message transmission between two computers on an insecure (e.g. public) network. |
| SSI | Server Side Include or Server Side Includes. |
| SSI commands | SSI stands for "server-side include," a type of HTML instruction telling a computer that serves Web pages to dynamically generate data, usually by inserting certain variable contents into a fixed template or boilerplate Web page. Used especially in database searches. |
| SSID | Service Set Identification. Sometimes referred to as the name of a wireless network. The two types of SSID are ESSID (for wireless networks with an access point) and BSSID (for ad-hoc wireless networks). |
| SSL | Secure Sockets Layer. Protocol for transmitting documents over the internet using a private key to encrypt the data. Originally developed by Netscape and now an industry standard. cf TLS, SHTTP, HTTPS. SSL is used in e-commerce websites for accepting credit card details on-line and for any site where it is important that the information cannot be gleaned by someone using a protocol analyzer. SSL ensures that data sent between a server and client is encrypted. On a web server, the SSL protocol (and corresponding encryption and decryption) occurs before the processing of the HTTP header information. For this reason a web server can only host a single secure website per unique IP address. The default TCP/IP port for SSL is port 443. |
| SSL (Secure Sockets Layer) | A protocol specified by Netscape that allows for “secure” passage of data. It uses public key encryption, including digital certificates and digital signatures, to pass data between a browser and a server. It is an open standard and is supported by most modern browsers. |
| SSMP (Simple Screen Management Protocol) | A communications protocol for text-based terminals. |
| Stack | A stack is a type of data structure -- a means of storing information in a computer. When a new object is entered in a stack, it is placed on top of all the previously entered objects. In other words, the stack data structure is just like a stack of cards, papers, credit card mailings, or any other real-world objects you can think of. When removing an object from a stack, the one on top gets removed first. This method is referred to as LIFO (last in, first out). The term "stack" can also be short for a network protocol stack. In networking, connections between computers are made through a series of smaller connections. These connections, or layers, act like the stack data structure, in that they are built and disposed of in the same way. |
| Stack Mashing | Stack mashing is the technique of using a buffer overflow to trick a computer into executing arbitrary code. |
| Standalone | A standalone device is able to function independently of other hardware. This means it is not integrated into another device. For example, a TiVo box that can record television programs is a standalone device, while a DVR that is integrated into a digital cable box is not standalone. Integrated devices are typically less expensive than multiple standalone products that perform the same functions. However, using standalone hardware typically allows the user greater customization, whether it be a home theater or computer system. Standalone can also refer to a software program that does not require any software other than the operating system to run. This means that most software programs are standalone programs. Software such as plug-ins and expansion packs for video games are not standalone programs since they will not run unless a certain program is already installed. |
| Standby | When electronic devices are receiving power but are not running, they are in standby mode. For example, a television is in standby mode when it is plugged in, but turned off. While the TV is not "on," it is ready to receive a signal from the remote control. An A/V receiver is also in standby mode when it is plugged in and turned off. This is because the receiver may be activated by receiving input from a connected device or by being turned on directly with the remote control. In other words, these devices are "standing by," waiting to receive input from the user or another device. When a computer is in standby mode, it is not completely turned off. Instead, it has already been turned on, but has gone into "sleep" mode. Therefore, when referring to computers, "Sleep" and "Standby" may be used synonymously. A computer in standby mode requires a small amount of current, called a "trickle charge," that keeps the current state of running software saved in the computer's RAM. However, because the computer is in sleep mode, the CPU, video card, and hard drive are not running. Therefore, the computer uses very little power in standby mode. Since standby mode saves energy, it is a good idea to put your computer to sleep if you are going to be away from it for more than 15 or 20 minutes. You can also use the Power Options control panel (in Windows) or the Energy Saver System Preference (in Mac OS X) to automatically put your computer to sleep after it has been inactive for a specific amount of time. Then, when you take a break from your computer, your computer can take a break as well. |
| Star Property | In Star Property, a user cannot write data to a lower classification level without logging in at that lower classification level. |
| start bit | Ancient modems alternated between two tones. One tone represented 0 and the other represented 1, which covered the entire binary language. Silence was not an option: to a modem, silence meant the phone call had been cut off. So when a modem had nothing to say, it continuously transmitted the 1 tone to tell the other modem that it was in an idle state. When there was more data to send, the modem would send a single 0 bit to say there was real data on the way. The next eight bits the receiving modem heard were the real data. Then the line went back to idle for at least one more bit. The 0 just before the data is called the start bit. The 1 at the end is the stop bit. |
| State Machine | A system that moves through a series of progressive conditions. |
| Stateful Inspection | The ability of a firewall to retain “state” information about ongoing network sessions. When a packet goes out through a stateful firewall (TCP/UDP/ICMP) it will only permit expected return traffic that would normally be returned in response to that packet from the remote site. This prevents spoofed packet attacks and other nasty things. |
| stateless | A stateless server (for example, a World Wide Web server) considers each page request independently. A request specifies the entire document, without requiring any context or memory of previous requests. Unless a cookie is set, no information is carried across requests. See also: cookie, state |
| Static Host Tables | Static host tables are text files that contain hostname and address mapping. |
| Static IP Address | An IP address that does not change. Most IP addresses for client machines are handed out by a method such as a DHCP server that manages a range of IP addresses. Static IP addresses are typically reserved for servers or routers, but some companies still use them for all their PCs. Most IP addresses handed out by an ISP are not static, but you can find ISPs that offer static IP addresses. |
| Static Routing | Static routing means that routing table entries contain information that does not change. |
| Static Website | A static website contains Web pages coded in HTML. The content of each page is fixed and does not change unless it is edited and republished by the webmaster. Static websites are usually small and only contain a few brochure-style Web pages. Large sites are typically designed as dynamic websites, since they are easier to maintain. |
| Status Bar | A status bar is a small area at the bottom of a window. It is used by some applications to display helpful information for the user. For example, an open folder window on the desktop may display the number of items in the folder and how many items are selected. Photoshop uses the status bar to display the size of the current image, the zoom percentage, and other information. Web browsers use the status bar to display the Web address of a link when the user moves the cursor over it. It also shows the status of loading pages, and displays error messages. If you don't see the status bar in your Web browser or another program, you may be able to enable it by selecting "Show Status Bar" from the application's View menu. If this option is not available in the View menu, the program may not use a status bar. Some programs use a "status window" instead to show the current activity in the application. The option for displaying this window is usually found in the "Window" menu. |
| Stealthing | Stealthing is a term that refers to approaches used by malicious code to conceal its presence on the infected system. |
| Steganalysis | Steganalysis is the process of detecting and defeating the use of steganography. |
| Steganography | Methods of hiding the existence of a message or other data. This is different than cryptography, which hides the meaning of a message but does not hide the message itself. An example of a steganographic method is "invisible" ink. |
| STEMMING | In keyword searching, word endings are automatically removed (lines becomes line); searches are performed on the stem + common endings (line or lines retrieves line, lines, line's, lines', lining, lined). Not very common as a practice, and not always disclosed. Can usually be avoided by placing a term in " ". |
| Stepping | The version of a particular chip. Microprocessors typically have many different steppings where performance is increased or minor bugs are fixed. The steppings are usually not touted as a new release of the chip because chips are not as easily upgradeable as software. You would have to buy a whole new chip to upgrade it. |
| Stimulus | Stimulus is network traffic that initiates a connection or solicits a response. |
| stop bit | The opposite of the start bit. See also: start bit |
| STOP WORDS | In database searching, "stop words" are small and frequently occurring words like and, or, in, of that are often ignored when keyed as search terms. Sometimes putting them in quotes " " will allow you to search them. |
| Storage Capacity | Storage capacity is another term for "disk space." It measures how much data a computer system may contain. For example, a computer with two 750GB hard drives has a storage capacity of 1.5TB. Storage capacity is commonly included in the technical specifications of a system, along with processing power and memory. It is possible to increase the storage capacity of most systems by adding additional internal or external hard drives. |
| Storage Device | A computer storage device is any type of hardware that stores data. The most common type of storage device, which nearly all computers have, is a hard drive. The computer's primary hard drive stores the operating system, applications, and files and folders for users of the computer. While the hard drive is the most ubiquitous of all storage devices, several other types are common as well. Flash memory devices, such as USB keychain drives and iPod nanos are popular ways to store data in a small, mobile format. Other types of flash memory, such as compact flash and SD cards are popular ways to store images taken by digital cameras. External hard drives that connect via Firewire and USB are also common. These types of drives are often used for backing up internal hard drives, storing video or photo libraries, or for simply adding extra storage. Finally, tape drives, which use reels of tape to store data, are another type of storage device and are typically used for backing up data. |
| Store-and-Forward | Store-and-Forward is a method of switching where the entire packet is read by a switch to determine if it is intact before forwarding it. |
| Straight-Through Cable | A straight-through cable is where the pins on one side of the connector are wired to the same pins on the other end. It is used for interconnecting nodes on the network. |
| Stream Cipher | A stream cipher works by encryption a message a single bit, byte, or computer word at a time. |
| Streaming | Data streaming, commonly seen in the forms of audio and video streaming, is when a multimedia file can be played back without being completely downloaded first. Most files, like shareware and software updates that you download off the Internet, are not streaming data. However, certain audio and video files like Real Audio and QuickTime documents can be streaming files, meaning you can watch a video or listen to a sound file while it's being downloaded to your computer. With a fast Internet connection, you can actually stream live audio or video to your computer. |
| streaming audio | Streaming audio solves a problem that used to discourage the use of sound on the Internet. Before streaming audio, Web users had to download an entire sound file before they could hear it. Because sound files tend to be fairly large, users had to wait a long time before they could hear the file. Web browsers can begin playing streaming audio files a few seconds after the download begins. In other words, you hear the file as it streams into your computer, rather than after it arrives. Streaming video does the same thing for digital movies, which are even bigger than digital sound files. |
| String | A string is a data type used in programming, such as an integer and floating point unit, but is used to represent text rather than numbers. It is comprised of a set of characters that can also contain spaces and numbers. For example, the word "hamburger" and the phrase "I ate 3 hamburgers" are both strings. Even "12345" could be considered a string, if specified correctly. Typically, programmers must enclose strings in quotation marks for the data to recognized as a string and not a number or variable name. For example, in the comparison: if (Option1 == Option2) then ... Option1 and Option2 may be variables containing integers, strings, or other data. If the values are the same, the test returns a value of true, otherwise the result is false. In the comparison: if ("Option1" == "Option2") then ... Option1 and Option2 are being treated as strings. Therefore the test is comparing the words "Option1" and "Option2," which would return false. The length of a string is often determined by using a null character. |
| Striping | Storing data across multiple disks in such a way that I/O read and write operations can proceed in parallel. Striping can give significant performance gains. cf RAID. |
| Strong Star Property | In Strong Star Property, a user cannot write data to higher or lower classifications levels than their own. |
| Sub Network | A separately identifiable part of a larger network that typically represents a certain limited number of host computers, the hosts in a building or geographic area, or the hosts on an individual local area network. |
| SUB-SEARCHING | Ability to search only within the results of a previous search. Enables you to refine search results, in effect making the computer "read" the search results for you selecting documents with terms you sub-search on. Can function much like RESULTS RANKING. |
| Subdirectory | A subdirectory, or subfolder, is a folder that is nested within another folder. Subdirectories are used to organize files and folders, which makes it easy to navigate to different files stored on a computer. While each operating system creates its own series of predefined subdirectories, you can also create new folders, which can be used to organize data in whatever way makes sense to you. |
| SUBJECT DIRECTORY | An approach to Web documents by a lexicon of subject terms hierarchically grouped. May be browsed or searched by keywords. Subject directories are smaller than other searchable databases, because of the human involvement required to classify documents by subject. |
| Subnet Mask | A subnet mask is a number that defines a range of IP addresses that can be used in a network. (It is not something you wear on your head to keep subnets out.) Subnet masks are used to designate subnetworks, or subnets, which are typically local networks LANs that are connected to the Internet. Systems within the same subnet can communicate directly with each other, while systems on different subnets must communicate through a router. Therefore, subnetworks can be used to partition multiple networks and limit the traffic between them. A subnet mask hides, or "masks," the network part of a system's IP address and leaves only the host part as the machine identifier. A common subnet mask for a Class C IP address is 255.255.255.0. Each section of the subnet mask can contain a number from 0 to 256, just like an IP address. Therefore, in the example above, the first three sections are full, meaning the IP addresses of computers within the subnet mask must be identical in the first three sections. The last section of each computer's IP address can be anything from 0 to 255. For example, the IP addresses 10.0.1.201 and 10.0.1.202 would be in the same subnet, while 10.0.2.201 would not. Therefore, a subnet mask of 255.255.255.0 allows for close to 256 unique hosts within the network (since not all 256 IP addresses can be used). If your system is connected to a network, you can typically view the network's subnet mask number in the Network control panel (Windows) or System Preference (Mac OS X). Most home networks use the default subnet mask of 255.255.255.0. However, some office networks may use a different subnet mask such as 255.255.255.128, which can be used to split a network into two subnets. Large networks with several thousand machines may use a subnet mask of 255.255.0.0. This is the default subnet mask used by Class B networks. The largest Class A networks use a default subnet mask of 255.0.0.0. |
| Subroutine | A mini program that resides inside another program and is called within that program. Typically you put together a subroutine when you have to do similar repetitive tasks in different areas of your program and you don’t want to code the same thing over and over again. |
| subscribe | Commonly refers to the act of selecting a network newsgroup as one you want to read on a regular basis or of sending a request to join a mailing list (discussion group) that interest you. The opposite action is called "unsubscribing". |
| Super Bypass | A means of reducing memory latency in the AMD 750 chipset, the first chipset designed to work with the AMD Athlon. It was implemented in all versions of the AMD 750, but did not function properly in early versions. AMD corrected this problem with a new revision of the AMD 750 chipset. It is possible to identify the Super Bypass-capable chipsets electronically or through software, but the enabling or disabling of Super Bypass is done automatically by the motherboard BIOS. |
| Super VGA (SVGA) | An extension to the original VGA standard which allows resolutions of 800×600. See also VGA. |
| Super XGA (SXGA) | A display with 1280×1024 pixel resolution. |
| Super XGA+ (SXGA+) | A display with 1400×1050 pixel resolution. It is a hybrid resolution between SXGA and UXGA found on some LCD screens in laptop PCs. |
| Supercomputer | As the name implies, a supercomputer is no ordinary computer. It is a high performance computing machine designed to have extremely fast processing speeds. Supercomputers have various applications, such as performing complex scientific calculations, modeling simulations, and rendering large amounts of 3D graphics. They may also be built to simply showcase the leading edge of computing technology. If you are hoping to have a supercomputer on your desk, you may be out of luck. Supercomputers are typically several times the size of a typical desktop computer and require far more power. A supercomputer may also consist of a series of computers, which may fill an entire room. Examples of single machine supercomputers include the early Cray-1 and Cray X-MP systems developed by Cray Research as well as the more recent Blue Gene and Roadrunner systems developed by IBM. System X is an example of a multi-system supercomputer, which was developed by Virginia Tech and is comprised of 1,100 Apple Xserve G5s. Supercomputers cost a fortune to build and are expensive to maintain, which is why only a few exist in the entire world. Furthermore, computing power continues to advance each year, meaning it isn't too long before a ground-breaking supercomputer isn't so super. The good news is that the supercomputers of the past eventually become the personal computers of today. Therefore, your home PC most likely has more computing power than many supercomputers from previous decades. Now that's super cool. |
| Supermicro | Super Micro Computer, Inc. or Supermicro (NASDAQ: SMCI) designs, develops, manufactures and sells servers based on the modular and open-standard x86 architecture. The company's solutions include rackmount server and blade server systems, high-end workstations, storage server systems, motherboards, chassis, and server components called Server Building Block Solutions®. |
| Surf (v. to surf) | This term is synonymous with browsing, as in browsing the Web with a Web browser. |
| Surge Protector | The surge protector is an important, yet often overlooked part of a computer setup. It allows multiple devices to plugged in to it at one time and protects each connected device from power surges. For example, a home office may have a computer, monitor, printer, cable modem, and powered speakers all plugged into one surge protector, which is plugged into a single outlet in the wall. The surge protector allows many devices to use one outlet, while protecting each of them from electrical surges. Surge protectors, sometimes called power strips, prevent surges in electrical current by sending the excess current to the grounding wire (which is the round part of the plug below the two flat metal pieces on U.S. outlet plugs). If the surge is extra high, such as from a lightning strike, a fuse in the surge protector will blow and the current will prevented from reaching any of the devices plugged into the surge protector. This means the noble surge protector will have given its life for the rest of the equipment, since the fuse is destroyed in the process. While surge protectors all perform the same basic function, they come in many shapes and sizes with different levels of protection. Some may look like basic power strips, while others may be rack mounted or fit directly against the wall. Most surge protectors offer six to ten different outlets. Cheaper surge protectors offer limited protection for surges (under 1000 joules), while more expensive ones offer protection for several thousand joules and include a monetary guarantee on connected devices if a power surge happens. Typically, you get what you pay for, so if you have an expensive computer system, it is wise to buy a quality surge protector that offers at least 1000 joules of protection. Some surge protectors also include line conditioning, which uses an electromagnet to maintain a consistent level of electricity when there are slight variations in current. For example, you might notice your computer monitor or television fade for a moment when you turn on a high-powered device, like a vacuum or air conditioner. A surge protector with line conditioning should prevent connected devices from being affected by these slight variances in current. While you may be able to hook up your computer system without a surge protector, it is important to protect your equipment by using one. You may not need a large, expensive surge protector with line conditioning, but using a quality surge protector for all your electronic devices is a smart choice. |
| SUS | Software Update Services. SUS is a Windows server add-on that makes it easier to deploy patches and other updates to a group of managed computers. Set to be superseded by WUS. |
| SVGA (Super VGA) | An extension to the original VGA standard which allows resolutions of 800×600. See also VGA. |
| Swap file | A file stored on the computer hard disk drive that is used as a temporary location to store information that is not currently being used by the computer RAM. By using a swap file a computer has the ability to use more memory than what is physically installed in the computer. However, users who are low on hard disk space may notice that the computer runs slower because of the inability of the swap file to grow in size. It is perfectly normal for the swap file or page file to grow in size, sometimes growing several hundred megs in size. Below is a listing of common Microsoft operating system swap file information; however, it is important to realize that this information may vary. Finally, by default the swap files are hidden. |
| Switch | 1. In a network, a switch is similar to a hub, in that it provides a central connection between two or more computers on a network, but with some intelligence. (A switch operates on Layer 2 (or above) of the OSI 7 layer model and a hub operates at Layer 1.) Whereas for a hub any message received at the hub is broadcast to all the attached computers, with a switch it is sent only to the destination computer and is not visible to other attached devices. This does not prevent "broadcast" messages from being sent to all attached devices. cf hub and router. 2. An electrical device used to turn current on and off. For example a light switch. 3. In software development languages, a switch statement is a control statement which allows one of a set of statements to be selected based on the value of some parameter. In some development languages a switch statement is known by the alternative name of a select statement (but do not confuse this with select in SQL which is not related.) |
| Switched Network | A communications network, such as the public switched telephone network, in which any user may be connected to any other user through the use of message, circuit, or packet switching and control devices. Any network providing switched communications service. |
| SXGA (Super XGA) | A display with 1280×1024 pixel resolution. |
| Symbolic Links | Special files which point at another file. |
| Symmetric Cryptography | A branch of cryptography involving algorithms that use the same key for two different steps of the algorithm (such as encryption and decryption, or signature creation and signature verification). Symmetric cryptography is sometimes called "secret-key cryptography" (versus public-key cryptography) because the entities that share the key. |
| Symmetric Key | A cryptographic key that is used in a symmetric cryptographic algorithm. |
| SYN | Abbreviation for Synchronize. |
| SYN Flood | A denial of service attack that sends a host more TCP SYN packets (request to synchronize sequence numbers, used when opening a connection) than the protocol implementation can handle. |
| Sync | When you "sync" a device, you synchronize it with your computer. Syncing is commonly done with iPods, PDAs, cell phones, and other electronic devices. The syncing process is also called "merging" the data because it copies the most recently entered information to each device. Therefore, when a device is synced with a computer, typically both the device and the computer are updated. Syncing may also refer to merging the data on two or more computer systems, which is often done over a network. |
| Synchronization | Synchronization is the signal made up of a distinctive pattern of bits that network hardware looks for to signal that start of a frame. |
| synchronous communication | Synchronous communication is the technique of choice for ISDN lines because it handles data more efficiently than the typical modem's asynchronous technique. While asynchronous communication sends smallish blocks of data with lots of control bits for error correction, synchronous techniques use big blocks of data with control bits only at the start and end of the entire transmission. But because of the minimal error checking, synchronous communicating devices must be timed to perfection, and they need a clean line. A modem used over an analog line won't handle synchronous communication well because a crackle on the line would throw everything out of sync. ISDN routers and internal adapters use synchronous communication. This allows them to transfer data up to 30 percent faster than ISDN modems, which must convert the data they receive synchronously so that it can be transmitted asynchronously through the computer's serial interface. See also: asynchronous communication |
| Synonym | A synonym is an alias for any table, view, snapshot, sequence, procedure, function or package contained within a database. |
| Syntax | Each spoken language has a general set of rules for how words and sentences should be structured. These rules are collectively known as the language syntax. In computer programming languages, syntax serves the same purpose, defining how declarations, functions, commands, and other statements should be arranged. Each computer programming language uses a different syntax. Many languages share similar syntax rules, while others have a very unique syntax design. For example, C and Java use a highly similar syntax, while Perl has many characteristics that are not seen in either the C or Java languages. Regardless of the rules, a program's source code must have the correct syntax in order to compile correctly and be made into a program. In fact, it must have the exact right syntax, or the program will fail to compile and produce a "syntax error." A syntax error can be as simple as a missing parenthesis or a forgotten semicolon at the end of a statement. Even these small errors will keep the source code from compiling. Fortunately, most software development programs include a debugger, which helps find the exact location of syntax errors within the source code. Imagine a program that has over ten thousand lines of code and a syntax error is caused by one missing semicolon. Finding a needle in a haystack would be preferred over manually locating the error. Needless to say, the debugger makes the debugging process much easier for the programmer. |
| synthesizer | An electronic musical instrument capable of generating sound using real-time control over the key parameters of sound: frequency, timbre, amplitude, and duration. Today most synthesizers include a MIDI interface. Also may refer to an internal sound card or external box for use with multimedia sequencing software. |
| Syslog | Syslog is the system logging facility for Unix systems. |
| System Analyst | A system analyst is the person who selects and configures computer systems for an organization or business. His or her job typically begins with determining the intended purpose of the computers. This means the analyst must understand the general objectives of the business, as well as what each individual user's job requires. Once the system analyst has determined the general and specific needs of the business, he can choose appropriate systems that will help accomplish the goals of the business. When configuring computer systems for a business, the analyst must select both hardware and software. The hardware aspect includes customizing each computer's configuration, such as the processor speed, amount of RAM, hard drive space, video card, and monitor size. It may also involve choosing networking equipment that will link the computers together. The software side includes the operating system and applications that are installed on each system. The software programs each person requires may differ greatly between users, which is why it is important that the system analyst knows the specific needs of each user. To summarize, the system analyst's job is to choose the most efficient computer solutions for a business, while making sure the systems meet all the company's needs. Therefore, the system analyst must have a solid understanding of computer hardware and software and should keep up-to-date on all the latest technologies. He must also be willing to listen to the constant needs and complaints of the users he builds systems for. |
| System Bus | The path between a microprocessor and the chipset on the motherboard. This bus may or may not run at the same speed as the memory bus. |
| System Hardening | Most computers offer network security features to limit outside access to the system. Software such as antivirus programs and spyware blockers prevent malicious software from running on the machine. Yet, even with these security measures in place, computers are often still vulnerable to outside access. System hardening, also called Operating System hardening, helps minimize these security vulnerabilities. The purpose of system hardening is to eliminate as many security risks as possible. This is typically done by removing all non-essential software programs and utilities from the computer. While these programs may offer useful features to the user, if they provide "back-door" access to the system, they must be removed during system hardening. Advanced system hardening may involve reformatting the hard disk and only installing the bare necessities that the computer needs to function. The CD drive is listed as the first boot device, which enables the computer to start from a CD or DVD if needed. File and print sharing are turned off if not absolutely necessary and TCP/IP is often the only protocol installed. The guest account is disabled, the administrator account is renamed, and secure passwords are created for all user logins. Auditing is enabled to monitor unauthorized access attempts. While these steps are often part of operating system hardening, system administrators may choose to perform other tasks that boost system security. While both Macintosh and Windows operating systems can be hardened, system hardening is more often done on Windows machines, since they are more likely to have their security compromised. |
| System Requirements | Whenever you purchase software or hardware for your computer, you should first make sure your computer supports the system requirements. These are the necessary specifications your computer must have in order to use the software or hardware. For example, a computer game may require you computer to have Windows XP or later, a 2.0 GHz processor, 512 MB or RAM, a 64 MB graphics card, and 500 MB or hard drive space. If your computer does not meet all of these requirements, the game will not run very well or might not run at all. It is just as important to check system requirements for hardware devices. For example, if you buy a printer, it may require either Windows XP or Mac OS X 10.3 or later. It may also require a USB port and 80 MB of available hard drive space. If your computer does not have any USB ports, you will not be able to physically connect the printer. If your machine does not have Windows XP or Mac OS X 10.3 or later, the printer drivers may be incompatible with your operating system. This means you computer will be unable to recognize the printer. Most hardware and software products have the system requirements printed on the side or bottom of the product packaging. When you are shopping for computer software or hardware, it is a good idea to first find out exactly what your system's specifications are and write them down on a piece of paper. The important information to record includes: Operating System (i.e. Windows XP, SP 2 or Mac OS X 10.3.8) Processor Speed (i.e. Pentium 4, 3.2 GHz or Power PC G5, 2.0 GHz) Memory, a.k.a. RAM (i.e. 512 MB) Graphics Card (i.e. ATI Radeon 9800 w/ 256 MB video memory) Hard Disk Space (i.e. 80 GB available) I/O Ports (i.e. USB, Firewire, Serial, Parallel, SCSI, VGA, DVI ports) By recording these specifications from your computer, you will be able to make sure your computer supports the products you are buying. |
| System Resources | Your computer has many types of resources. They include the CPU, video card, hard drive, and memory. In most cases, the term "system resources" is used to refer to how much memory, or RAM, your computer has available. For example, if you have 1.0 GB (1024 MB) of RAM installed on your machine, then you have a total of 1024 MB of system resources. However, as soon as your computer boots up, it loads the operating system into the RAM. This means some of your computer's resources are always being used by the operating system. Other programs and utilities that are running on your machine also use your computer's memory. If your operating system uses 300 MB of RAM and your active programs are using 200 MB, then you would have 524 MB of "available system resources." To increase your available system resources, you can close active programs or increase your total system resources by adding more RAM. System resources can also refer to what software is installed on your machine. This includes the programs, utilities, fonts, updates, and other software that is installed on your hard drive. For example, if a file installed with a certain program is accidentally removed, the program may fail to open. The error message may read, "The program could not be opened because the necessary resources were not found." As you can see, the term "system resources" can be a bit ambiguous. Just remember that while it usually refers to your computer's memory, it can be used to describe other hardware or software as well. |
| System Security Officer (SSO) | A person responsible for enforcement or administration of the security policy that applies to the system. |
| System Software | System software refers to the files and programs that make up your computer's operating system. System files include libraries of functions, system services, drivers for printers and other hardware, system preferences, and other configuration files. The programs that are part of the system software include assemblers, compilers, file management tools, system utilites, and debuggers. The system software is installed on your computer when you install your operating system. You can update the software by running programs such as "Windows Update" for Windows or "Software Update" for Mac OS X. Unlike application programs, however, system software is not meant to be run by the end user. For example, while you might use your Web browser every day, you probably don't have much use for an assembler program (unless, of course, you are a computer programmer). Since system software runs at the most basic level of your computer, it is called "low-level" software. It generates the user interface and allows the operating system to interact with the hardware. Fortunately, you don't have to worry about what the system software is doing since it just runs in the background. It's nice to think you are working at a "high-level" anyway. |
| System Unit | This is the technical term that refers to the box that houses your computer. The system unit refers to the computer itself but does not include the monitor, the keyboard, the mouse, or any other peripherals. I suppose most people will probably know what you mean when you refer to "the box," but saying "system unit" will definitely make you sound more sophisticated. |
| System-Specific Policy | A System-specific policy is a policy written for a specific system or device. |
| Systray | The systray, short for "system tray," is located on the right side of the Windows toolbar. It is the collection of small icons on the opposite side of the Start Menu. The volume control and the date & time are default items in the systray and many more can be added. Some common icons that get placed in the systray are virus-scan, mouse, and instant messenger icons. They usually get put in the systray (whether you like it or not) when their respective programs are installed. The nice thing about the systray is that it allows quick and easy access to programs and control settings. Most systray icons will open a control panel or program when double-clicked. However, if you install too many of them, the area can get so cluttered, you may find it easier to just browse your hard drive and open the program. |
