Glossary terms provided by TechTerms.com.
| Word | Description |
| U | U is the standard unit of measurement for rack-mounted equipment. Racks can be used to house servers, hard drives, switches, routers, and other computer hardware. They are also used for mounting audio and video equipment. Standard racks are 24 inches wide, but vary in height. For this reason, the U unit measures how tall a rack-mountable hardware device is. 1U is equal to 1.75 inches. Therefore, a 1U piece of equipment is 1.75 inches tall and takes up one unit of rack space. A 2U device is 3.5 inches tall and takes up 2 units of rack space. Racks themselves are also measured in U. For example, a 10U rack could store 10 1U devices or 5 2U devices. |
| UAC | User Account Control. A system built into Windows Vista where the operating system warns the user if an application tries to install or overwrite installed programs, and requests authorisation from the user before allowing the activity to go ahead. UAC is intended to increase the security of Windows Vista by making the user (administrator) aware each time an application performs something which has the potential to compromise security. Whilst UAC can be disabled (which administrators may be tempted to to to avoided the repeated prompting it generates) it is generally advised to leave it enabled. |
| UART (Universal Asynchronous Receiver Transmitter) | A chip that standardized serial communications. Its function is to change a byte into a standard sequence of electrical impulses. |
| UBE | Unsolicited Broadcast E-mail. Unsolicited e-mail - otherwise more commonly known as spam. |
| UBR | 1. Unspecified Bit Rate. No guarantee of available bandwidth. 2. Universal Bandwidth Router. |
| Ubuntu (operating system) | Ubuntu (pronounced /uːˈbuːntuː/),[3][4] is a computer operating system based on the Debian GNU/Linux distribution. It is named after the Southern African ethical ideology Ubuntu ("humanity towards others")[5] and is distributed as free and open source software. Ubuntu provides an up-to-date, stable operating system for the average user, with a strong focus on usability and ease of installation. Ubuntu has been selected by readers of desktoplinux.com as the most popular Linux distribution for the desktop, claiming approximately 30% of Linux desktop installations in both 2006 and 2007.[6][7] Web statistics from late 2009 suggest that Ubuntu's share is between 40 and 50%.[8][9] Ubuntu is composed of multiple software packages, of which the vast majority are distributed under a free software license (also known as open source). The main license used is the GNU General Public License (GNU GPL) which, along with the GNU Lesser General Public License (GNU LGPL), explicitly declare that users are free to run, copy, distribute, study, change, develop and improve the software. Ubuntu is sponsored by the UK-based company Canonical Ltd., owned by South African entrepreneur Mark Shuttleworth. By keeping Ubuntu free and open source, Canonical is able to utilize the talents of community developers in Ubuntu's constituent components. Instead of selling Ubuntu for profit, Canonical creates revenue by selling technical support and from creating several services tied to Ubuntu. Canonical endorses and provides support for three additional Ubuntu-derived operating systems: Kubuntu, Edubuntu and Ubuntu Server Edition. There are several other derivative operating systems including local language and hardware-specific versions.[10] Canonical releases new versions of Ubuntu every six months and supports Ubuntu for eighteen months by providing security fixes, patches to critical bugs and minor updates to programs. LTS (Long Term Support) versions, which are released every two years,[11] are supported for three years on the desktop and five years for servers. |
| UCE | Unsolicited Commercial E-mail, i.e. Spam distributed with the aim of commercial gain. |
| UDDI | Universal Description, Discovery and Integration. A method for finding new Web Services by referring to a central directory. The specification for an index of all available Web services which is comparable to a global Yellow-Pages directory. UDDI helps businesses to produce descriptions of the services they offer, pass on details to the registry and thus appear to be a services provider. Using the UDDI method, Web services users can send enquiries in the form of SOAP messages to the central registration point to ascertain suppliers of a particular service. |
| UDF | 1. Universal Disc Format. A disc format for optical media (such as cds and dvds) which is designed to be supportable by any operating system and not be tied to a single operating system. UDF is defined by ISO/IEC 13346 (also known as ECMA-167) and is widely viewed as a successor to ISO 9660 (which defined the file system for CD-ROMs). |
| UDMA (Ultra DMA) | short for Ultra DMA |
| UDP | 1. User Datagram Protocol. Like TCP, UDP sits above IP, but unlike TCP it is a connectionless communications protocol (meaning there is no handshaking between the sender and receiver). It provides a "best-effort" delivery, and neither the arrival or correct sequencing of datagrams is guaranteed. Datagrams can therefore go missing without any form of notification. UDP is used by applications that do not require an acknowledgement and which send only small amounts of data. It is typically used to broadcast information over a network. |
| UDP (User Datagram Protocol) | Part of the TCP/IP suite of protocols. UDP is the part of the TCP/IP suite used by applications to transfer datagrams. It is also the part of TCP/IP responsible for port addresses. UDP got the short end of the stick in some ways in that its name isn’t included in TCP/IP. |
| UDP Scan | UDP scans perform scans to determine which UDP ports are open. |
| UID | Unique Identifier or Unique ID. A generic term used to refer to any form of unique identifier - which can be used to uniquely identify something within the system or context in which it was generated. UID is sometimes used as an abbreviation for an account user name. |
| ULSI (Ultra Large Scale Integration) | A microchip with over one million transistors. Most popular chips today fit this description. Maybe in 10 years we will have the SDULSI, for Super-Duper Ultra Large Scale Integration. For now this is at the top of the heap. See also VLSI, LSI, MSI, and SSI. |
| Ultra 160M (160M) | A form of SCSI that supercedes Ultra2 SCSI. It runs at up to 160 megabytes per second and uses 80-pin connections over copper wires. |
| Ultra 320M (320M) | A form of SCSI that doubles the potential performance of Ultra 160M SCSI and offers throughput of up to 320 megabytes per second per channel. |
| Ultra ATA/100 | Another extension to the ATA interface that adds a 50% increase in top speed over ATA/66, getting to 100MB/second, up from 66MB/second. This standard also adds some additional error-checking not found in earlier ATA standards. Like Ultra ATA/66, ATA/100 requires an 80-conductor cable to work at full speed. |
| Ultra ATA/133 | This refers to what is most probably the final extension to the parallel ATA connection standard. The proposal was created by Maxtor, and allows a top data transfer rate of 133 megabytes per second. Intel didn’t support this standard in its chipsets, instead opting to wait for Serial ATA. See Serial ATA for further details. |
| Ultra ATA/33 | An extension to the ATA interface (IDE) that effectively doubles the top data transfer speed of IDE from 16.6MBytes/second up to 33 MBytes/second. Also known as Ultra-IDE. |
| Ultra ATA/66 | An extension to the ATA interface (IDE) proposed by Quantum that effectively doubles the data transfer speed of the Ultra ATA/33 interface to 66MBps. To achieve the increase in speed you must use a special 80-conductor cable with 40 data lines and 40 ground lines to keep the signal stable. |
| Ultra DMA | This technology for transferring data between a computer's hard disk and memory was developed by Quantum and Intel. The maximum burst rate of an Ultra DMA hard drive is 33.3 MBps. The original DMA (Direct Memory Access) protocol could only transfer data at half that speed. Thanks to Ultra DMA, programs can open faster and run more smoothly. This is because Utlra DMA can send more data to the memory in less time than the original DMA. Ultra DMA also has a built-in utility called Cyclical Redundancy Checking (CRC) that helps protect data integrity. So if you want a nice, fast hard drive, look for one that supports Ultra DMA. |
| Ultra DMA (Ultra ATA/33) | An extension to the ATA interface (IDE) that effectively doubles the top data transfer speed of IDE from 16.6MBytes/second up to 33 MBytes/second. Also known as Ultra-IDE. |
| Ultra SATA (Serial ATA) | A specification for consumer hard drive connections that boosts the data transfer rate up to 150MB/second. In addition, it changes IDE/ATA from a parallel interface requiring 40 separate wires to connect components to a serial interface requiring only 6 wires. 2x and 4x versions of Serial ATA double and quadruple the speed of Serial ATA. |
| Ultra SCSI | This is SCSI that communicates twice as fast as standard SCSI-2. Normal Ultra-SCSI transfers data at 20MBps, and Wide Ultra-SCSI transfers data at 40MBps. Similar to Ultra-IDE, Ultra-SCSI works its magic by transferring data on the up AND the down stroke of a clock cycle, doubling throughput. |
| Ultra XGA (UXGA) | A display with 1600×1200 pixel resolution. |
| Ultra2 SCSI (LVD) | This standard doubles the maximum transmission speed of Ultra SCSI. Almost all devices made to this standard support the 80MBps transfer rate of Ultra2 Wide SCSI. See also LVD. |
| Ultra3 SCSI | Ultra3 SCSI doubles the maximum transfer rate of Ultra2 SCSI up to 160MBps. This is synonymous with 160M SCSI. |
| UNC | Stands for "Universal Naming Convention," not just the home of the North Carolina Tar Heels. UNC is a filename format that is used to specify the location of files, folders, and resources on a local-area network (LAN). The UNC address of a file may look something like this: \\server-name\directory\filename UNC can also be used to identify peripheral devices shared on the network, including scanners and printers. It provides each shared resource with a unique address. This allows operating systems that support UNC (such as Windows) to access specific resources quickly and efficiently. |
| Undoable disk mode | All writes to an undoable disk issued by software running inside the virtual machines appear to be written to the disk, but are in fact stored in a temporary file (.REDO) on the host file system for the duration of the session. When the virtual machine is powered down, the user is given three choices: (1) permanently apply all changes to the disk; (2) discard the changes, thus restoring the disk to its previous state; or (3) keep the changes, so that further changes from future sessions can be added to the log. |
| Unicast | Broadcasting from host to host. |
| uniformity | An ideal monitor will deliver equal brightness across the entire screen. In practice, however, many monitors have darker areas or appear patchy, demonstrating a lack of uniformity. These problems are particularly easy to spot on a white background. |
| Unix | A computer operating system (the basic software running on a computer, underneath things like word processors and spreadsheets). Unix is designed to be used by many people at the same time (it is multi-user) and has TCP/IP built-in. It is the most common operating system for servers on the Internet. Apple computers' Macintosh operating system, as of version 10 ("Mac OS X"), is based on Unix. See also: Linux, Server, TCP/IP |
| Unmount | Unmounting a disk makes it inaccessible by the computer. Of course, in order for a disk to be unmounted, it must first be mounted. When a disk is mounted, it is active and the computer can access its contents. Since unmounting a disk prevents the computer from accessing it, there is no risk of the disk being disconnected in the middle of a data transfer. Therefore, before removing an external data storage device, such as a USB flash drive, the disk should be unmounted to avoid possible data corruption. Several types of disks can be unmounted, including external hard drives, USB flash drives, iPods, flash memory cards, and disk images. In order to unmount a disk in Windows, open "My Computer," select the disk, and click the "Eject this disk" option in the left sidebar. In Mac OS X, select the disk on the desktop and either drag the disk to the trash (which changes to an Eject icon), or select "File->Eject" from the Finder's menu bar. Once a removable disk has been unmounted, it can safely be disconnected from the computer. |
| Unprotected Share | In Windows terminology, a "share" is a mechanism that allows a user to connect to file systems and printers on other systems. An "unprotected share" is one that allows anyone to connect to it. |
| UP | 1. Unified Process. 2. In computing "Up" is usually used to mean "On and working". For example "is the server up?" is a question asking whether the server is working and available. cf Down. |
| Upgrade | This normally refers to a newer version of software, or a version with an enhanced feature set. If you already own a previous version of the software, you can often purchase an upgrade version for a lower price than a new version. In terms of hardware, you can upgrade your system by adding more memory, or any component that makes your system better or faster. Some graphics cards let you upgrade them by plugging more memory onto the board. |
| Uplink Port | A special networking port on a hub or switch that is used to connect it to a larger network. Often you need a special crossover cable to make this connection function properly. If you think of a network as a tree, the hub (or switch) on top connects to the uplink ports of the hubs (or switches) below it, and so on. |
| Upload | To transmit (or copy) data from a local computer to a remote computer via a network, modem, serial or parallel cable. For example to copy a file from a local computer to a server via FTP you would be said to be uploading the file (in this case by FTP). cf Download. |
| UPnP | Stands for "Universal Plug and Play." Plug and Play describes devices that work with a computer system as soon as they are connected. UPnP is an extension of this idea that expands the range of Plug and Play devices to networking equipment. Universal Plug and Play uses network protocols to allow a wide range of devices to be interconnected and work seamlessly with each other. UPnP devices can be connected via wired (i.e. Ethernet and Firewire) or wireless (i.e. Wi-Fi and Bluetooth) connections. As long as a product supports UPnP, it can communicate with other UPnP devices within a network. The connections are typically created using the DHCP networking protocol, which assigns each connected device a unique IP address. While UPnP is helpful for setting up networks, it also can be used to set up compatible audio and video (AV) devices. UPnP AV is a group of standards based on UPnP that allows audio and video components to be connected via network connections. This enables media files and streaming data to be sent between devices. For example, a movie stored on a hard drive in a bedroom could be played back on the TV screen in the living room. The central controller of a UPnP AV network is called a MediaServer and can be run from a Macintosh, Windows, or Linux computer or from a hardware device specifically designed to manage the network. Since most UPnP devices support zero-configuration setup (like ordinary Plug and Play devices), it is simple to add devices to a network and use them immediately. While the networking terms associated with UPnP can be a bit intimidating, setting up a UPnP network is meant to be hassle-free ? and that is a term we can all appreciate. |
| UPS | Uninterruptible Power Supply. A battery backup device that supplies AC power automatically in the event of a power failure. There are two basic types of UPS, "stand-by" and "on-line": Stand-by power supply or SPS. A device powered by an SPS is normally powered directly from the mains, with the battery charging. The batter is the stand-by power supply. Should the power fail then the power supply is switched to the battery (via an inverter). SPS has the advantage of being cheaper than the on-line version but does not provide an instant change over of power nor does it provide any mains filtering and therefore they are not suitable for all applications. On-line. Here the battery to AC inverter is always connected to the output of the UPS. While mains power is available the battery will recharge, and should the mains power fail the switch to batter power is almost instantaneous. Thus there is almost no risk of interruption of supply should the power fail. They normally also provide some form of mains filtering but are generally more expensive than the SPS variety. |
| Upstream | This refers to sending of data from a client machine across the Internet. With cable modems and ADSL, upstream speeds are slower than downstream speeds. |
| URI | Uniform Resource Identifier. A UNI is a way to identify (or address) a name or resource over a network. A URI is expressed as a short string. A URI takes the form of a URN or a URL. |
| URL | Uniform Resource Locator. A URL provides a standard way to address any resource on the internet. URLs are expressed as a text string of the form: protocol://domain-name/pathname Where protocol is any valid protocol, such as http, ftp, gopher etc. One example of a URL that most people are now familiar with is the web address of each site and page. See also: URI, URN. URLs are defined by RFC1738 and RFC1808. Whilst the HTTP specification does not limit the length of a URL, most browsers do have a limiting maximum size. Whilst this limit is far in excess of most browsing requests, current limits are: Browser / Server Limit Source Internet Explorer (browser) 2083 characters Microsoft Knowledge Base Article 208427 Netscape (browser) No limit Apache (web server) 8190 characters (default) www.jetools.com/content/resources/whitepapers/HTTP_GET_Requests.pdf IIS 6.0 (web server) 16KB |
| URN | Uniform Resource Name. A URN provides a standard way to name a resource. URNs are expressed as a text string of the form: urn://nid/nss Where nid indicates the namespace and nss the namespace specific string. For example: urn://isbn/0674362500 refers to a book (on Greek) See also URL. |
| USB | Universal Serial Bus. USB provides a single common interface to peripherals and plug-and-play configuration (at the host/pc). The original standard for USB (occasionally referred to as USB 1.0, but normally simply as USB) supported transfer speeds of 1.5Mbps and 12Mbps. USB 1.1 is a revised version of the USB specification, but the transfer rate remains unchanged. USB 2.0 (also referred to as "USB Hi-Speed) also supports 480Mbps and is otherwise backwards compatible with earlier versions. The USB specification limits maximum cable lengths to 5m for high speed USB devices and 3m to low speed devices USB. USB Version Supported speeds Maximum cable length 1.5Mbps 12Mbps 480Mbps USB 2.0 5m USB 1.1 3m USB 1.0 3m |
| USB port | An interface used for connecting a Universal Serial Bus (USB) device to computer; these ports support plug and play |
| USENET | A world-wide system of discussion groups, with comments passed among hundreds of thousands of machines. Not all USENET machines are on the Internet. USENET is completely decentralized, with over 10,000 discussion areas, called newsgroups. |
| User Contingency Plan | User contingency plan is the alternative methods of continuing business operations if IT systems are unavailable. |
| User Datagram Protocol (UDP) | Part of the TCP/IP suite of protocols. UDP is the part of the TCP/IP suite used by applications to transfer datagrams. It is also the part of TCP/IP responsible for port addresses. UDP got the short end of the stick in some ways in that its name isn’t included in TCP/IP, but would you really want to call it TCP/UDP/IP? |
| User Interface | A user interface is the means in which a user controls a software program or hardware device. For example, a software interface may include windows, icons, menus, and buttons that allow the user to interact with the program. This is also known as a graphical user interface, or GUI. A hardware interface can be a remote control or a video game controller. It may also refer to the controls on a camcorder, digital camera, or iPod. Most modern user interfaces today are designed using a combination of hardware and software. Example: "The Apple iPhone has a touchscreen user interface." |
| Username | A username is a name that uniquely identifies someone on a computer system. For example, a computer may be setup with multiple accounts, with different usernames for each account. Many websites allow users to choose a username so that they can customize their settings or set up an online account. For example, your bank may allow you to choose a username for accessing your banking information. You may need to choose a username in order to post messages to a certain message board on the Web. E-mail services, such as Hotmail require users to choose a username in order to use the service. A username is almost always paired with a password. This username/password combination is referred to as a login, and is often required for users to log in to websites. For example, to access your e-mail via the Web, you are required to enter your username and password. Once you have logged in, your username may appear on the screen, but your password is kept secret. By keeping their password private, people can create secure accounts for various websites. Most usernames can contain letters and numbers, but no spaces. When you choose a username for an e-mail account, the part before the "@" is your username. |
| UTC | Coordinated Universal Time (UTC). It is the current term for what used to be commonly referred to as Greenwich Meridian Time (GMT). |
| Utility | Utility programs, commonly referred to as just "utilities," are software programs that add functionality to your computer or help your computer perform better. These include antivirus, backup, disk repair, file management, security, and networking programs. Utilities can also be applications such as screensavers, font and icon tools, and desktop enhancements. Some utility programs help keep your computer free from unwanted software such as viruses or spyware, while others add functionality that allows you to customize your desktop and user interface. In general, programs that help make your computer better are considered utilities. And unlike water and electric bills, computer utilities don't send you a bill every month! |
| Utility computing | Utility computing is the packaging of computing resources, such as computation and storage, as a metered service similar to a traditional public utility (such as electricity, water, natural gas, or telephone network). This system has the advantage of a low or no initial cost to acquire hardware; instead, computational resources are essentially rented. Customers with very large computations or a sudden peak in demand can also avoid the delays that would result from physically acquiring and assembling a large number of computers. "Utility computing" has usually envisioned some form of virtualization so that the amount of storage or computing power available is considerably larger than that of a single time-sharing computer. Multiple servers are used on the "back end" to make this possible. These might be a dedicated computer cluster specifically built for the purpose of being rented out, or even an under-utilized supercomputer. The technique of running a single calculation on multiple computers is known as distributed computing. The term "grid computing" is often used to describe a particular form of distributed computing, where the supporting nodes are geographically distributed or cross administrative domains. To provide utility computing services, a company can "bundle" the resources of members of the public for sale, who might be paid with a portion of the revenue from clients. One model, common among volunteer computing applications, is for a central server to dispense tasks to participating nodes, on the behest of approved end-users (in the commercial case, the paying customers). Another model, sometimes called the Virtual Organization (VO),[citation needed] is more decentralized, with organizations buying and selling computing resources as needed or as they go idle. The definition of "utility computing" is sometimes extended to specialized tasks, such as web services. |
| UTP (Unshielded Twisted Pair) | Cables that consist of pairs of unshielded wire twisted together. These cables are used for data and telephone networks. They are cheap to produce because they are unshielded, and they get their shielding by being twisted together in pairs. |
| UXGA (Ultra XGA) | A display with 1600×1200 pixel resolution. |
