Glossary terms provided by TechTerms.com.
| Word | Description |
| H.323 | n ITU-T standard for transferring multimedia videoconferencing data over packet-switched networks, such as TCP/IP. There is a LAN standard for high-quality video, and an Internet standard for lower-bandwidth video over lines as slow as 28.8Kbits. |
| Hacker | While this term originally referred to a clever or expert programmer, it is now more commonly used to refer to someone who can gain unauthorized access to other computers. A hacker can "hack" his or her way through the security levels of a computer system or network. This can be as simple as figuring out somebody else's password or as complex as writing a custom program to break another computer's security software. Hackers are the reason software manufacturers release periodic "security updates" to their programs. While it is unlikely that the average person will get "hacked," some large businesses and organizations receive multiple hacking attempts a day. |
| HAL | 1. Hardware Abstraction Layer. Part of the Windows kernel responsible for much of the interfacing to hardware devices. |
| Half Duplex | Allowing simultaneous sending and receiving of data, but data is sent at a lower speed than it is received. cf Full Duplex. |
| handshaking | The initial negotiation period immediately after a connection is established between two modems. This is when the modems agree about how the data will be transmitted (e.g., error correction, packet size, etc.). The set of rules they agree on is called the protocol. |
| Hard Copy | A hard copy is a printed document. It may be a text file, photograph, drawing, or any other type of printable file. For example, instead of e-mailing a business memo, it may be sent out as a hard copy, or an actual physical paper containing the memo. When a document is created on a computer, it is typically saved as a file on the the computer's hard drive. This is sometimes referred to as a soft copy. While the file can be easily opened and edited on a computer, it can also be easily deleted. Therefore, sometimes printing a hard copy is done to create a physical backup of the document. |
| hard disk | A storage device that holds large amounts of data, usually in the range of hundreds to thousands of megabytes. Although usually internal to the computer, some types of hard disk devices are attached separately for use as supplemental disk space. "Hard disk" and "hard drive" often are used interchangeably but technically, hard drive refers to the mechanism that reads data from the disk. |
| Hard Drive | The hard drive is what stores all your data. It houses the hard disk, where all your files and folders are physically located. A typical hard drive is only slightly larger than your hand, yet can hold over 100 GB of data. The data is stored on a stack of disks that are mounted inside a solid encasement. These disks spin extremely fast (typically at either 5400 or 7200 RPM) so that data can be accessed immediately from anywhere on the drive. The data is stored on the hard drive magnetically, so it stays on the drive even after the power supply is turned off. The term "hard drive" is actually short for "hard disk drive." The term "hard disk" refers to the actual disks inside the drive. However, all three of these terms are usually seen as referring to the same thing -- the place where your data is stored. Since I use the term "hard drive" most often, that is the correct one to use. |
| Hard Reset (Hardware Reset) | This refers to the forced, immediate shutdown and restart of a PDA or other device by means of hardware. This is typically done by pushing a sequence of buttons or a reset button, and usually only after it has become impossible to do a soft reset. |
| Hard Token | A hard token, sometimes called an "authentication token," is a hardware security device that is used to authorize a user. An common example of a hard token is a security card that gives a user access to different areas of building or allows him to log in to a computer system. Some hard tokens are used in combination with other security measures to further enhance security. For example, a username and password or a fingerprint scan may be required along with the hard token to gain access to a secure system. A hard tag is another type of hard token that is used as a security device on merchandise such as clothing and electronics. You have probably seen these used in several retail stores, where they are used to deter theft. If someone tries to exit the building with merchandise before the hard tag has been deactivated, it causes the security system by the doors to beep. Of course, if the cashier forgets to deactivate the hard tag, you get to experience the unpleasant beeping sound as you exit even if you paid for the merchandise. |
| Hardening | Hardening is the process of identifying and fixing vulnerabilities on a system. |
| Hardware | Computer hardware refers to the physical parts of a computer and related devices. Internal hardware devices include motherboards, hard drives, and RAM. External hardware devices include monitors, keyboards, mice, printers, and scanners. The internal hardware parts of a computer are often referred to as components, while external hardware devices are usually called peripherals. Together, they all fall under the category of computer hardware. Software, on the other hand, consists of the programs and applications that run on computers. Because software runs on computer hardware, software programs often have system requirements that list the minimum hardware required for the software to run. |
| Hardware Emulation Layer (HEL) | This provides software-based emulation of features that are not directly available in hardware. |
| Harvest | Another name for the act of capturing web content as a part of crawling. |
| Hash Function | An algorithm that computes a value based on a data object thereby mapping the data object to a smaller data object. |
| Hash Functions | (cryptographic) hash functions are used to generate a one way "check sum" for a larger text, which is not trivially reversed. The result of this hash function can be used to validate if a larger file has been altered, without having to compare the larger files to each other. Frequently used hash functions are MD5 and SHA1. |
| Hash table | A table that contains “hash values,” generally used for speeding up searching algorithms on sorted data. For example, a hash table for a dictionary might contain all the letters of the alphabet and the page numbers where each letter starts. That way, instead of searching through from start to finish for each word, you just use the hash table and get a big head start. |
| HCL (Hardware Compatibility List) | A list of computers and peripherals that have been tested by Microsoft to work with Windows NT or Windows 2000. If you run those operating systems on equipment that is not listed on the HCL, it is not guaranteed to work, but it might. Basically, if you install NT/2000 on hardware that’s not on the HCL, you are on your own. However, it is done frequently with decent success. |
| HD | 1. Hard Disk. cf FDD, HDD. 2. High Density. 3. High Definition. Normally used in the context of High Definition TV (HDTV). |
| HDD | 1. Hard Disk Drive. Also referred to simply as HD. See also IDE, SCSI, SMART. 2. Hybrid Disk Drive. A (standard) Hard Disk Drive that incorporates flash memory as a buffer (likely minimum of 1GB of flash). When compared to a traditional disk drive, a hybrid disk driver offers: significantly improved start-up times for PCs (because most of the files required at start-up can be read from the flash memory rather than the disk). power savings (and corresponding longer battery life for laptops) because the flash memory will allow most writes to be cached (in non volatile storage) allowing the disk spindle to be powered down for much of the time. |
| HDTV | HDTV High Definition Television. A television display standard providing much better picture quality than a standard (non-HD) television. There are a number of different formats for high-definition, a TV which supports any one of these standards can claim to be high-definition (or HD Ready): 720p 1080i 1080p The number part specifies the number of vertical lines. 720p is 720 vertical lines (and 1280 lines horizontally). 1080i and 1080p are both 1080 vertical lines (and 1920 lines horizontally). HDTV are always widescreen, so having a horizontal to vertical ratio of 16:9 The letter "p" or "i" denotes "progressive" or "interlaced" respectively, which denotes how the picture is built up. With interlaced the image is built up in two passes, with every other line updated on each pass. With progressive scan a complete image is transmitted in each frame. What this means in practice is that progressive gives a smoother picture, especially where there is notion. Occasionally the format may be expressed with an additional number after the "p" or "i". Where this is given this is the frame frame, i.e. the number of frames per second. Typically 720p is 60 frames per second (so 720p60 in full), and 1080i and 1080p are 50 frames per second. cf SDTV, NTSC, PAL, EDTV |
| HEAD or HEADER | The top portion of the HTML source code behind Web pages, beginning with and ending with . It contains the Title, Description, Keywords fields and others that web page authors may use to describe the page. The title appears in the title bar of most browsers, but the other fields cannot be seen as part of the body of the page. To view the portion of web pages in your browser, click VIEW, Page Source. In Internet Explorer, click VIEW, Source. Some search engines will retrieve based on text in these fields. |
| header | The portion of an e-mail message or a network newsgroup posting that precedes the body of the message; it contains information like who the message is from, its subject, and the date. A header also is the portion of a packet that proceeds the actual data and contains additional information the receiver will need. |
| Heap | Most commonly, this is a segment of memory claimed by a program. Within the heap, pieces of memory can be used and freed as needed. Depending on usage, heaps can become fragmented as small pieces of memory are used and freed. In formal computer science terms, a heap is the same as a partially ordered tree. |
| Heat Sink | A computer's CPU may perform millions of calculations every second. As the processor continues to work at a rapid pace, it begins to generate heat. If this heat is not kept in check, the processor could overheat and eventually destroy itself. Fortunately, CPUs include a heat sink, which dissipates the heat from the processor, preventing it from overheating. The heat sink is made out of metal, such as a zinc or copper alloy, and is attached to the processor with a thermal material that draws the heat from away the processor towards the heat sink. Heat sinks can range in size from barely covering the processor to several times the size of the processor if the CPU requires it. Most heat sinks also have "fins," which are thin slices of metal that are connected to the base of the heat sink. These additional pieces of metal further dissipate the heat by spreading it over a much larger area. A fan is often used to cool the air surrounding the heat sink, which prevents the heat sink from getting too hot. This configuration is referred to as a heat sink and fan or HSF combination. While heat sinks are used in nearly all computer CPUs, they have become commonplace in video card processors, or GPUs, as well. |
| Helper Application | A program allowing you to view multimedia files (images, audio, video) that your web browser cannot handle internally. The file must be downloaded before it will be displayed. There are some plug-ins that allow you to view the file over the Internet without downloading it first. See Also: Browser, Plug-in |
| Heuristic | A rule of thumb for solving a problem. A heuristic provides a quick means of solving a problem, utilising a known rule of thumb, trick or simplification to arrive at a solution to a problem in a shorter time than other conventional methods. Heuristics are not guaranteed to solve a problem or to provide the optimal solution. Heuristics are sometimes also referred to as Heuristic Algorithms. |
| heuristics | A method of analyzing outcome through comparison to previously recognized patterns. For example, an antivirus program, familiar with behaviors typical of viruses (such as deleting files in sequence), could use heuristics to identify unknown virus strains by their behavior. |
| Hewlett-Packard (HP) | Hewlett-Packard Company (NYSE: HPQ), commonly referred to as HP, is a consumer electronics corporation headquartered in Palo Alto, California, USA. HP is the world's largest technology company and operates in nearly every country. HP specializes in developing and manufacturing computing, storage, and networking hardware, software and services. Major product lines include personal computing devices, enterprise servers, related storage devices, as well as a diverse range of printers and other imaging products. HP markets its products to households, small to medium size businesses and enterprises both directly, via online distribution, consumer-electronics and office-supply retailers, software partners and major technology vendors. |
| HEX | 1. Hexadecimal. A base 16 numbering system, which uses the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F. So: Hex Decimal Octal Binary 0 0 0 0000 1 1 1 0001 2 2 2 0010 3 3 3 0011 4 4 4 0100 5 5 5 0101 6 6 6 0110 7 7 7 0111 8 8 10 1000 9 9 11 1001 A 10 12 1010 B 11 13 1011 C 12 14 1100 D 13 15 1101 E 14 16 1110 F 15 17 1111 10 16 20 10000 Hexadecimal is used in IT because of its close relationship to Binary - as can be seen from the above table each hexadecimal digit corresponds to 4 bits. This means that the hexadecimal numbers 0 to FF cover all the possible eight bit values of a byte (0 to 255 decimal). Depending on the context, hexidecimal numbers are sometimes prefixed with 0x or # to indicate that the number is hexadecimal and not decimal. 2. Hexagonal. A flat six sided shape. |
| HFS | Stands for "Hierarchical File System." HFS is the file system used for organizing files on a Macintosh hard disk. When a hard disk is formatted for a Macintosh computer, the hierarchical file system is used to create a directory that can expand as new files and folders are added to the disk. Since HFS is a Macintosh format, Windows computers cannot recognize HFS-formatted drives. Windows hard drives are typically formatted using WIN32 or NTFS file systems. Since HFS was not originally designed to handle large hard disks, such as the 100GB+ hard disks that are common today, Apple introduced a updated file system called HFS+, or HFS Extended, with the release of Mac OS 8.1. HFS+ allows for smaller clusters or block sizes, which reduces the minimum size each file must take up. This means disk space can be used much more efficiently on large hard disks. Mac OS X uses the HFS+ format by default and also supports journaling, which makes it easier to recover data in case of a hard drive crash. |
| Hibernate | This allows computer users to save the contents of their computer’s memory to disk before shutting down the PC. When restarted, the contents are read back into RAM and the computer is brought back to the exact state it was in before hibernation was initiated. This is different from sleep mode, where the computer is not fully shut down. |
| HIDS | Host based Intrusion Detection System. A system for detecting unauthorised access to a single computer. A HIDS may monitor logs or activity on network ports, or use other techniques to detect possible intrusions. cf Intrusion Detection System (IDS). |
| Hijack Attack | A form of active wiretapping in which the attacker seizes control of a previously established communication association. |
| HISTORY, Search History | Available by using the combined keystrokes CTRL + H. You can set how many days your browser retains history in Edit | Preferences, or in Tools | Options. |
| hit | As used in reference to the World Wide Web, ?hit? means a single request from a web browser for a single item from a web server; thus in order for a web browser to display a page that contains 3 graphics, 4 ?hits? would occur at the server: 1 for the HTML page, and one for each of the 3 graphics. |
| Hive | A sub-tree of the Windows registry. |
| HKCR | Common abbreviation for the Windows registry root ‘HKEY_CLASSES_ROOT’, one of the Windows registry hives. |
| HKLM | Common abbreviation for the Windows registry root ‘HKEY_LOCAL_MACHINE’, one of the Windows registry hives. |
| HMI | Human Machine Interface. See also MMI. |
| Homepage | A page on the World Wide Web (WWW) that is the first page of a website. Usually it is called index.html or index.htm. When you go to a Web address, this is the first page your browser looks for. |
| Honey Client | see Honeymonkey. |
| Honey pot | Programs that simulate one or more network services that you designate on your computer's ports. An attacker assumes you're running vulnerable services that can be used to break into the machine. A honey pot can be used to log access attempts to those ports including the attacker's keystrokes. This could give you advanced warning of a more concerted attack. |
| Honeymonkey | Automated system simulating a user browsing websites. The system is typically configured to detect web sites which exploit vulnerabilities in the browser. Also known as Honey Client. |
| Honeypot | A system left open and unprotected to entice hackers to break into it. Usually this is done so that system administrators can monitor the methods used to break in, the frequency of attack, or just to throw off attackers from the real goodies. |
| Hop | One piece of the TCP/IP networking protocol route that a computer needs to take in order to send or receive information. Think of all the main computers in the world that are physically connected as stones in a lake. To get from your stone to the stone on the other side you need to “hop” on a certain number of other stones. A similar method is used for communicating over the Internet. |
| Hops | A hop is each exchange with a gateway a packet takes on its way to the destination. |
| Host | Any computer on a network that is a repository for services available to other computers on the network. It is quite common to have one host machine provide several services, such as SMTP (email) and HTTP (web). |
| Host adapter | his term is synonymous with SCSI adapter. It refers to an add-in board, such as a PCI SCSI card, that allows PCs to communicate with SCSI devices. |
| Host OS | The operating system hosting one or more virtual machines (or partitions) and sharing physical resources with them. It's where the virtualization product or the partitioning product is installed. |
| Host-Based ID | Host-based intrusion detection systems use information from the operating system audit records to watch all operations occurring on the host that the intrusion detection software has been installed upon. These operations are then compared with a pre-defined security policy. This analysis of the audit trail imposes potentially significant overhead requirements on the system because of the increased amount of processing power which must be utilized by the intrusion detection system. Depending on the size of the audit trail and the processing ability of the system, the review of audit data could result in the loss of a real-time analysis capability. |
| Host-only networking | A type of network connection between a virtual machine and the host. Under host-only networking, a virtual machine is connected to the host on a private network, which normally is not visible outside the host. Multiple virtual machines configured with host-only networking on the same host are on the same network. |
| Hosted Environment | A virtual environment where the virtualization product is installed on top of a host OS, instead of being installed on physical hardware. The opposite of bare metal environment. |
| Hot Spare | A drive in a RAID configuration that sits idle until one of the RAIDed drives fails. The hot spare then assumes the role of the dead drive. When the dead drive is replaced you can make it the hot spare. (The old hot spare doesn’t revert back because it’s got data on it now.) Hot spares are most often used in RAID 5 configurations, but can also be used in RAID 1 or RAID 10. When a drive fails the hot spare must be populated with information regenerated from the other drives. During this time performance is degraded. |
| Hot-pluggable | Same as hot-swappable, but also connotes a simple plug-in mechanism for easy swapping. |
| Hot-swappable | This type of mechanism implies that you can remove or add things while the system is powered on and running. For example, hard drives and power supplies are often candidates for this term, but more expensive servers may even have hot-swappable memory, PCI cards, and processors. Normally they come in special proprietary form factors in server machines and RAID boxes. If you’ve got mission-critical applications, you want your servers to have as many hot swappable components as possible. |
| Hotmail | free email service, now part of MSN. |
| Hover | When you roll the cursor over a link on a Web page, it is often referred to as "hovering" over the link. This is somewhat like when your boss hovers over you at work, but not nearly as uncomfortable. In most cases, the cursor will change from a pointer to a small hand when it is hovering over a link. Web developers can also use cascading style sheets (CSS) to modify the color and style of link when a user hovers over it. For example, the link may become underlined or change color while the cursor is hovering over it. The term hovering implies your computer screen is a three-dimensional space. In this conception, your cursor moves around on a layer above the text and images. When you click the mouse button while the cursor is hovering over a link, it presses down on the link to activate it. Hovering can also be used in a more general sense such as moving the cursor over icons, windows, or other objects on the screen. |
| HPC | 1. High Performance Computing. HPC is a generic and relative term since the desktop computers of today are capable of the same performance as supercomputers from a few years back. Thus because of progress in computing technology, a computer once deemed capable of high performance computing might no longer be regarded as a HPC a year or two later. HPC is often associated with (so called) super computers, and parallel processing. Parallel processing requiring both suitable hardware and suitable software design. 2. Handheld PC. A HPC is a small portable handheld computer. HPC means that same as "PDA", but is a less popular acronym. |
| HT | Common abbreviation for Hyper-Threading. |
| HTML | Hyper Text Mark-up Language. Used to construct web pages. By convention HTML pages composed on Windows platforms have the .htm file extension, whilst pages composed on other platforms tend to use the .html file extension. See also: http, https. |
| HTML (HyperText Markup Language) | A standard language initially created for typesetting. Although it is a language, it isn’t really a programming language. It is mainly used for creating documents on the World Wide Web. Included in the language are provisions for displaying graphics and links to other pages. |
| HTTP | HTTP Hypertext Transfer Protocol. Network protocol for the transfer of web or intranet pages (for subsequent display or other purpose). HTTP is not a secure protocol. All communications with HTTP occurs in plain text. cf HTTPS and SHTTP. HTTP typically uses port 80 (the default port for HTTP), but the protocol allows for other port numbers to be used. Since some ISPs block port 80, typical alternative ports are port 8080 and 8000, but these are by convention and are not part of the HTTP standard. |
| HTTP (HyperText Transfer Protocol) | The way the data in an HTML document is transferred. A document coming in over the HTTP protocol, usually TCP/IP port 80, is read as an HTML document. You may notice in our Internet browser’s address bar that the address begins with “HTTP://” in order to tell the browser to expect HTML files. |
| HTTPS | Hypertext Transmission Protocol Secure (or Hypertext Transmission Protocol Security) is HTTP over SSL. In reality HTTPS is more often HTTP over TLS. HTTPS is used when web page information needs to be kept secure and private, such as when dealing with private, commercial or financial information across the internet. HTTPS is essential for all e-commerce applications. The default port for HTTPS is port 443, but theoretically there is no reason why a site might not use a different port provided the client was aware of it. HTTPS and SHTTP are not the same, although both provide enhanced security above that of HTTP. |
| HTTPS (Secure HyperText Transfer Protocol) | 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. |
| Hub | Generic term for any device which connects two or more computers or devices together on a network allowing them to communicate. The term hub is sometimes (incorrectly) used to refer to a switch, the difference being that a hub is a simple unintelligent repeater forwarding all incoming packets to everything on the network. cf router and switch. |
| HW | 1. Common abbreviation for Hardware (Hard-Ware). 2. Abbreviation for Hand-Written. |
| Hybrid Attack | A Hybrid Attack builds on the dictionary attack method by adding numerals and symbols to dictionary words. |
| Hybrid Encryption | An application of cryptography that combines two or more encryption algorithms, particularly a combination of symmetric and asymmetric encryption |
| Hyper-Threading | Intel trademark term for multi-threading in in the Pentium 4 micro-architecture. Hyper-Threading enables the processor to execute multiple threads in parallel on the same processor. Hyper-Threading allows different threads to execute in parallel provided the two threads do not require access to the same execution resource on the CPU at the same time. Hyper-threading can give a significant performance boost to some applications. It is not the same as having physically separate CPUs and performance will not be as good as a dual-CPU arrangement. To take advantage of Hyper-Threading you must be running on an operating system that can take advantage of it (such as Windows XP, Windows 2003 or an appropriate Unix/Linux build) and running with a motherboard and processor that support it. Hyper-Threading has been reported to be incompatible with some applications. Hyper-Threading can often be disabled in the BIOS. Hyper-Threading is commonly abbreviated to HT. The technology is also known more generically as SMT (Simultaneous Multithreading Technology). |
| Hyperlink | In hypertext or hypermedia, an information object (such as a word, a phrase, or an image; usually highlighted by color or underscoring) that points (indicates how to connect) to related information that is located elsewhere and can be retrieved by activating the link. |
| Hypertext | Generally, any text that contains links to other documents - words or phrases in the document that can be chosen by a reader and which cause another document to be retrieved and displayed. See also: HTML, HTTP |
| HyperThreading | Slightly abbreviated term for Hyper-Threading. |
| Hypervisor | The virtualization software layer managing hardware requests from a guest OS, simulating answers from a real hardware. Used as VMM (Virtual Machine Monitor) synonymous. |
| Hz | Hertz, the standard unit for measuring frequency. One hertz is one (complete) cycle per second, 100hz is 100 cycles per second and so on. The Hz unit can be applied to any type of frequency, but is more commonly used when measuring sound or AC electricity. For example, electricity in most of Europe is distributed at 50Hz (whilst some countries distribute electricity at 60Hz). The human ear is generally regarded as being capable of hearing sounds in the frequency range 20hz to 20,000Hz (20khz). Other related units: 1,000Hz = 1KHz 1,000,000Hz = 1MHz 1,000,000,000Hz = 1GHz |
| Hz (hertz) | short for hertz |
| H_Key (Hive_Key) | A part of the Windows registry hive. The hive contains several different pieces, or keys. |
