Glossary terms provided by TechTerms.com.
| Word | Description |
| e-book | The concept behind an e-book is that it should provide all the functionality of an ordinary book but in a manner that is (overall) less expensive and more environmentally friendly. The actual term e-book is somewhat confusingly used to refer to a variety of things: custom software to play e-book titles, dedicated hardware to play e-book titles, and the e-book titles themselves. Individual e-book titles can be free or commercial (but will always be less expensive than their printed counterparts) and have to be loaded into a player to be read. Players vary wildly in capability level. Basic ones allow simple reading and bookmarking; better ones include various features like hypertext, illustrations, audio, and even limited video. Other optional features allow the user to mark-up sections of text, leave notes, circle or diagram things, highlight passages, program or customize settings, and even use interactive fiction. |
| This stands for electronic mail. It is a service provided over the Internet that allows you to send information to another person or list of people. | |
| e-mail alias or e-mail forwarding | Not every e-mail address has its own POP3 or Web-based mailbox. Some merely redirect e-mail traffic to another e-mail address. These P.O. Box-style addresses are called aliases or e-mail forwarding addresses. Domain hosts or registrars offer them as a service to people who register domains but don't want to reconfigure their e-mail software to pick up from another e-mail box--or pay for space on an e-mail server. |
| Easter egg | Brightly colored protochickens? Not always. Easter eggs are also "hidden features" placed by programmers in software applications, operating systems, and even some hardware. Discover the hidden command sequence, and an Easter-egged product will perform an action, such as displaying a secret message or playing a sound or small animation. |
| Eavesdropping | Eavesdropping is simply listening to a private conversation which may reveal information which can provide access to a facility or network. |
| ECC | Error Correcting Code. An error correction code is additional data sent with a message which allows the recipient to identify whether the data has become corrupted in transit and to correct the error. The number of errors (typically the number of bit errors) which can be corrected will depend on the amount of error correction applied. |
| Echo Reply | An echo reply is the response a machine that has received an echo request sends over ICMP. |
| Echo Request | An echo request is an ICMP message sent to a machine to determine if it is online and how long traffic takes to get to it. |
| EDI | Electronic Data Interchange. The transfer of data electronically between computers. The term is typically used to denote the transfer of data electronically across a network between two separate organisations. There are a wide range of standards for electronic data interchange, the two most common are ANSI X12 end EDIFACT. |
| EDIFACT | EDI for Administration, Commerce and Transport. This refers to the United Nations rules for EDI for Administration, Commerce and Transport. ISO standard 9735. |
| EFS | Encrypting File System. Strengthens security by encrypting files on the hard disk so that no one can access them without using the correct password. Encrypted files are visible only to the individual who encrypted them. This is handled seamlessly by EFS, so the owning user can still browse and open files as normal - at the same time preventing others from doing so. Encrypted files can also be recovered using the recovery agent - which uses certificates and public keys to decrypt files. |
| EFT | Electronic Funds Transfer. A system where money is transferred electronically from one bank account to another, without the need for any paper work such as the traditional cheque. |
| EGA (Enhanced Graphics Adapter) | The standard that came after CGA and before VGA. It allowed resolutions up to 640×350 pixels and 16 colors from a palette of 64. It was soon replaced by VGA. EGA images look squished because the aspect ratio of 640×350 is not flattering compared to the more standard 640×480 resolution of VGA that corresponded exactly to the 4:3 aspect ratio of most computer monitors. |
| Egress Filtering | Filtering outbound traffic. |
| EIDE | Enhanced IDE. See ATA. |
| eLearning | lectronic learning; applies to a wide scope of processes including Web-based learning, computer-based instruction, virtual classrooms, and digital collaboration. Content may be delivered in a variety of ways including via the Internet, satellite broadcast, interactive TV, and DVD- or CD-ROMs. |
| Electromagnetic Field (EMF) | A form of radiation given off by all electrical devices. Most notably for computer users, CRT computer monitors used to give off potentially dangerous amounts of EMF radiation, especially from the sides and rear. This radiation was blamed for causing miscarriages and even cancer. Newer monitors are heavily shielded and give off much lower levels of radiation, especially through the front, where users typically sit. |
| 1. Electronic Mail. Virtually instantaneous electronic messaging. cf SMTP, snail mail, spam, email address. Email can be written as either "email" or "e-mail". 2. Email Address. For details see email address. | |
| Email Address | Electronic mail address. For the recipient of an email, the email address is the address to which the email is sent. For a sender each (outgoing) email should identify the sender's email address (to allow for replies). An email address consists of two parts, a username and a domain (or host) name with an at symbol ('@') separating them. The domain specifies which server the email should be delivered to and the username tells the server at that domain which mailbox to deposit the email into. |
| Emanations Analysis | Gaining direct knowledge of communicated data by monitoring and resolving a signal that is emitted by a system and that contains the data but is not intended to communicate the data. |
| Embedded Memory | This is memory that is built directly onto a processor. For example, a graphics chip may have embedded memory instead of using separate memory chips. Use of embedded memory in PCs and PC components nowadays is fairly rare, as attaching a large amount of memory to a chip reduces yields and increases costs. |
| Embedded Processor | A microprocessor used in an embedded system. Typically these processors are smaller, consume less power, and utilize a surface mount form factor, as opposed to more standard consumer processors. Embedded processors are only sold to consumers pre-built into embedded systems, not separately. |
| Embedded System | A system that is located entirely on a processor. All logic is contained in a single chip and has a single purpose. New cars have many embedded systems working to keep emissions low and performance high. |
| EMEA | Europe, Middle East and Africa. Refers to a large geographic region encompassing Europe, the Middle East and Africa. |
| EMF | A form of radiation given off by all electrical devices. Most notably for computer users, CRT computer monitors used to give off potentially dangerous amounts of EMF radiation, especially from the sides and rear. This radiation was blamed for causing miscarriages and even cancer. Newer monitors are heavily shielded and give off much lower levels of radiation, especially through the front, where users typically sit. |
| emoticon | A combination of keyboard characters meant to represent a facial expression. Frequently used in electronic communications to convey a particular meaning, much like tone of voice is used in spoken communications. Examples: the characters :-) for a smiley face or ;-) for a wink. |
| Emulation | The term "emulation" comes from the verb "emulate," which means to imitate or reproduce. Therefore, computer emulation is when one system imitates or reproduces another system. This can be done using hardware, software, or a combination of the two. However, since hardware is expensive to reproduce, most emulation is done via software. One of the most common types of software emulation involves running different operating systems in a virtual environment. For example, programs like Parallels Desktop, VMware, and Apple's Boot Camp allow Windows and other operating systems to run on an Intel-based Macintosh computer. Sun Microsystems' xVM VirtualBox allows multiple operating systems to be run on Windows, Mac, and Unix platforms. These applications are collectively referred to as software emulators, since they emulate different computer systems. Another popular type of software emulation allows console video games, such as Nintendo, Sega, and PlayStation games, to be run on a PC. The program ZSNES, for example, allows Super Nintendo (SNES) games to be played on a Windows or Unix machine. The Virtual Boy Advance emulator allows users to play Game Boy Advance games on Windows or Macintosh computers. Games for these emulators are saved as ROM files, which are exact copies of a game cartridge or disk. Therefore, instead loading a physical cartridge, video game emulators simply load ROM files from the computer's hard drive. A third type of emulation uses a type of file called a disk image. While ROM files are used to emulate game cartridges, disk images can be used to emulate optical media and physical hard disk. For example, an .ISO file (Windows) or .DMG file (Mac) can be mounted on the desktop, which makes the operating system view the file as a physical disk. This provides an easy way to make exact copies of CDs, DVDs, and hard disks. Disk images are also commonly used to create virtual installer disks that can't be modified by the user. A software technology allowing an operating system or an application to run on hardware other than the one for which it was developed. |
| Emulator | This is usually a program that performs the same operation of another program or a piece of hardware. For example, there are programs that allow a PC to act like a Commodore 64, a Nintendo Entertainment System, or even a Macintosh. These emulators are often developed by talented programmers just to prove that something can be done. |
| Encapsulation | The inclusion of one data structure within another structure so that the first data structure is hidden for the time being. |
| Encryption | A method of protecting data by transforming it in such as way that a reader cannot understand the data unless they know the decryption mechanism. Encryption algorithms come in two general types: Symmetric algorithms and Asymmetric algorithms. Symmetric algorithms uses the same key to encrypt and decrypt. Asymmetric algorithms use a different key to encrypt and decrypt. See also: DES, RAS |
| Enterprise | The entirety of an organization that uses computers. Typically it refers to very large corporations, or software or hardware solutions designed for large organizations. Enterprise companies usually have numerous locations and hundreds, if not thousands, of users to support–a scenario which requires an entirely different type of IT system and management than a small to mid-sized company. |
| Environment | Normally this is your surroundings. Inside your computer, the environment is the settings of a group of variables. Think of it as the surroundings or boundaries set for a process or program running inside your computer. Instead of having a wall and a door, a program in your PC may have x=4 and name=”Tara” as its environment. |
| EPC | Earnings Per Click. Terms used by various affiliate schemes (where webmasters utilise some of the space on web pages for advertisements) to indicate the average earnings per click. EPC is only a guide, because most clicks will generate any revenue. |
| Ephemeral Port | Also called a transient port or a temporary port. Usually is on the client side. It is set up when a client application wants to connect to a server and is destroyed when the client application terminates. It has a number chosen at random that is greater than 1023. |
| EPROM | erasable programmable ROM Unlike dynamic and static RAM, EPROM chips do not require power to retain their data. Consequently, EPROM chips are commonly used to store BIOS information and basic software for modems, video cards, and other peripherals. EPROMs can be erased by exposure to ultraviolet light and then reprogrammed using a device called a PROM burner. See also: BIOS, DRAM, EEPROM, RAM, ROM, SRAM |
| Error | This occurs in a program when it encounters a situation that it was not programmed to deal with. If errors are trapped properly, they can be dealt with by the program itself. If not, they will be dealt with by the operating system on which the program is running. |
| Error Checking and Correcting (ECC) | This generally refers to memory chips or motherboards that support the checking for, and possibly correcting of, memory errors in full-parity memory chips. ECC memory uses some extra memory on the memory chips for parity information, and checks to see whether a memory error has occurred. If a minor (one-bit) memory error occurs, the ECC logic will handle it. With full-parity memory (one step below ECC), you will be alerted of a memory error and your system will stop. With non-parity memory you will experience random results, usually crashing, and possible data corruption. If a two-bit or larger error occurs in ECC memory, your system will be halted–similar to what happens with parity memory when any error is encountered. Many caches built into computer microprocessors now have ECC features. |
| Escrow Passwords | Escrow Passwords are passwords that are written down and stored in a secure location (like a safe) that are used by emergency personnel when privileged personnel are unavailable. |
| ESSID | Extended Service Set ID. The ESSID is the identifying name of a wireless network - strictly it is the identifying name of a wireless access point. It allows one wireless network to be clearly distinguishable from another. ESSID is one type of SSID (the other being BSSID). |
| EST | 1. Eastern Standard Time. The time zone used on the East coast of America and Canada. 2. Abbreviation for Established. When used in this way it is normally followed by a year, for example "Est. 2001", meaning established in 2001. 3. Abbreviation for Estimated. For example, "est. population" would mean "estimated population". |
| ESX | VMware ESX is an enterprise-level virtualization product offered by VMware, Inc. ESX is a component of VMware's larger offering, VMware Infrastructure, which adds management and reliability services to the core server product. The basic server requires some form of persistent storage—typically, an array of hard disk drives—for storing the virtualization kernel and support files. A variant of this design, VMware ESXi, does away with the first requirement by moving the server kernels into a dedicated hardware device. Both variants support the services offered by VMware Infrastructure.[2] |
| ESXi | VMware ESX is an enterprise-level virtualization product offered by VMware, Inc. ESX is a component of VMware's larger offering, VMware Infrastructure, which adds management and reliability services to the core server product. The basic server requires some form of persistent storage—typically, an array of hard disk drives—for storing the virtualization kernel and support files. A variant of this design, VMware ESXi, does away with the first requirement by moving the server kernels into a dedicated hardware device. Both variants support the services offered by VMware Infrastructure.[2] |
| Ethernet | A very common method of networking computers in a LAN. There is more than one type of Ethernet. By 2001 the standard type was "100-BaseT" which can handle up to about 100,000,000 bits-per-second and can be used with almost any kind of computer. |
| EULA | End User License Agreement. |
| EULA (End User License Agreement) | The contract found in most software packages that describes the rights to which the user of the software is entitled. Typically, it will explain how many people can use the software, whether it can be used on multiple machines, and whether it is transferable. |
| Event | An event is an observable occurrence in a system or network. |
| event handler | An event is an action that occurs on a Web page, such as clicking a link or changing the value of a text area. An event may be performed by the user or forced by a script. In JavaScript, an event handler is a mechanism for causing a script to react to an event. For example, if you set the onClick event handler equal to a function call or a JavaScript statement, and include the event handler as an attribute in a link, the code will be executed when the user clicks the link. |
| Evergreening | policy for keeping software and hardware resources up to date. For example a simple evergreening policy might be to replace all computers older than four years with new models. cf "technology replacement", "technology refresh". An evergreening policy should state whether the purpose is to replace technology to maintain an acceptable level of reliability (mean time between failure), to acquire improved speed and capacity at an acceptable price or a combination of the two (i.e. to acquire the lowest or lower cost technology replacement with speed and capacity at least as good as its predecessor). cf "Technology Refresh" and "Technology Replacement". |
| Exabyte | Unit of storage. Often abbreviated to EB. 1 exabyte (EB) = 2 to the sixtieth power (260) bytes = 1,152,921,504,606,846,976 bytes = 1024 petabytes = one billion gigabytes. See also zettabyte. |
| Excel | Microsoft Excel is a spreadsheet program for Windows and Macintosh computers. It is part of the Microsoft Office suite, which includes other productivity programs, such as Word and PowerPoint. Though Excel is developed by Microsoft, the first version of the program was released for the Macintosh in 1985. It wasn't until 1987, when Microsoft introduced Windows 3.0, that Excel was made available for Windows. Since then, Microsoft has supported the program on both platforms, releasing updates about every two years. Some other popular spreadsheet programs include IBM Lotus 1-2-3 (for Windows) and the AppleWorks spreadsheet program (for the Mac). However, Microsoft Excel has led the spreadsheet market for many years and continues to be the most popular spreadsheet program for both businesses and consumers. |
| EXE File | An executable file or application. Normally denoted by a file with a ".exe" file extension. Take care when deleting because executable files. On Windows systems it is preferable to use the Install/Uninstall applet in the Windows Control Panel to remove programs. If you receive an email attachment that is an executable file then only execute it if it is from a known and trusted source because many viruses spread by sending exe files as e-mail attachments. |
| Execution Unit | The part of a microprocessor pipeline that actually follows and runs the instructions that are sent to the CPU after the instructions are decoded. |
| Expansion Card | An expansion card is a printed circuit board that can be installed in computer to add functionality to it. For example, a user may add a new graphics card to his computer to give it more 3D graphics processing power. An audio engineer may add a professional sound card to his machine to increase the computer's audio input and output connections. Users that need more Firewire or USB ports can add Firewire or USB expansion cards, which provide additional connections. Most expansion cards are installed in PCI slots. This includes variations of PCI, such as PCI-X and PCI Express. Graphics cards may also be installed in an AGP slot, which is designed specifically for video cards. Since expansion cards require open slots, they can only be installed in computers that have available expansion slots. Therefore, computers like the Apple iMac and other all-in-one machines cannot accept expansion cards. Computer towers, however, often have two or three open expansion slots, and can accept multiple cards. Laptops don't use traditional expansion cards because of their small form factor. However, some models can accept removable PCMCIA cards that add extra ports or other functionality to the computer. |
| Expansion Slot | Any type of slot in a computer into which you can plug an expansion card. Examples include ISA, EISA, PCI,PCI-X, and PCMCIA, but there are other types and there will be more in the future. |
| Exploit (n. exploit) | A means of gaining access to a computer system, typically through a known bug in a program or operating system. Many webservers on the Internet that are not up to date with security patches are vulnerable to exploits, and the effects of these exploits are seen when malicious worms run rampant and spread to unpatched systems. |
| Exponential Backoff Algorithm | An exponential backoff algorithm is used to adjust TCP timeout values on the fly so that network devices don't continue to timeout sending data over saturated links. |
| Export | en you export data you are taking that data from a program, database, or file and saving it in another format that is generally easier to manipulate or pull into a different program. An example would be pulling data from a SQL database and saving it as text so that you can use it in a mailmerge. Thus, the exporting frees the mailmerge program from having to understand the complex SQL format–it just needs to understand the exported text file. |
| Exposure | A threat action whereby sensitive data is directly released to an unauthorized entity. |
| Extended ACLs (Cisco) | Extended ACLs are a more powerful form of Standard ACLs on Cisco routers. They can make filtering decisions based on IP addresses (source or destination), Ports (source or destination), protocols, and whether a session is established. |
| Extended partition | A type of partition that is an extension of a primary partition. It’s possible to have many extended partitions on a hard drive. |
| Extensible Authentication Protocol (EAP) | A framework that supports multiple, optional authentication mechanisms for PPP, including clear-text passwords, challenge-response, and arbitrary dialog sequences. |
| Extension (File Extension) | DOS, Windows, and, to a lesser extent, UNIX and Linux use the last three characters of a filename, after a period, to signify what type of file a file is, such as text, movie, sound, etc. The MacOS has a file system that contains an identifier for file types that is invisible when looking at the filename, and allows you to call files whatever you want without a messy extension on the end. Some common examples are: .exe (executable file), .bat (batch file), .wav (wave sound file), and .txt (text file). |
| Exterior Gateway Protocol (EGP) | A protocol which distributes routing information to the routers which connect autonomous systems. |
| External Hard Drive | Nearly all personal computers come with an internal hard drive. This drive stores the computer's operating system, programs, and other files. For most users, the internal hard drive provides enough disk space to store all the programs and files. However, if the internal hard drive becomes full or if the user wants to back up the data on the internal hard drive, and external hard drive may be useful. External hard drives typically have one of two interfaces ? USB or Firewire. USB hard drives commonly use the USB 2.0 interface because it supports data transfer rates of up to 480 Mbps. USB 1.1 only supports transfers of up to 12 Mbps, which would make the hard drive seem slow to even the most patient people. Firewire drives may use either Firewire 400 or Firewire 800, which support data transfer rates of up to 400 and 800 Mbps respectively. The most likely users to need external hard drives are those who do audio and video editing. This is because high-quality media files can fill up even the largest hard drives. Fortunately, external hard drives can be daisy chained, which means they can be connected one after the other and be used at the same time. This allows for virtually unlimited amounts storage. Users who do not require extra storage may still find external hard drives useful for backing up their main hard drive. External hard drives are a great backup solution because they can store an exact copy of another hard drive and can be stored in a safe location. Using the drive to restore data or perform another backup is as simple as connecting it to the computer and dragging the necessary files from one drive to another. While most external hard drives come in heavy, protective cases, some hard drives are designed primarily for portability. These drives usually don't hold as much data as their larger desktop counterparts, but they have a sleek form factor and can easily be transported with a laptop computer. Some portable drives also include security features such as fingerprint recognition that prevent other people from accessing data on the drive in case it is lost. |
| Extranet | An intranet that is accesible to computers that are not physically part of a companys' own private network, but that is not accessible to the general public, for example to allow vendors and business partners to access a company web site. Often an intranet will make use of a Virtual Private Network. (VPN.) |
