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Glossary terms provided by TechTerms.com.
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Word Description
T&C Terms and Conditions. A stated list of terms and conditions that must be agreed to by a user of a service as a condition of use of that service. Sometimes also referred to as TOS or TOU.
T-1 A leased-line connection capable of carrying data at 1,544,000 bits-per-second. At maximum theoretical capacity, a T-1 line could move a megabyte in less than 10 seconds. That is still not fast enough for full-screen, full-motion video, for which you need at least 10,000,000 bits-per-second. T-1 lines are commonly used to connect large LANs to theInternet.
T-3 A leased-line connection capable of carrying data at 44,736,000 bits-per-second. This is more than enough to do full-screen, full-motionvideo.
T1 Two pairs of copper wire that carry data at a rate of 1.544Mbps. T1 lines are used to carry 24 DS-0 signals. They can be used to carry 24 phone lines or an Internet connection capable of 1.544Mbps data transfer. See also fractional T1.
T2 Four T1 lines which can carry 96 voice channels or up to 6.312Mbps worth of data.
T3 28 T1 lines together make up a T3, which can carry 672 separate voice channels or up to 44.736Mbps data throughput.
T4 6 T3 lines make up a T4, which carries data at 274Mbps.
T5 240 T1 lines, which can carry 5760 voice channels or up to 400.352Mbps worth of data.
table With reference to web design, a method for formatting information on a page. Use of tables and the cells within also provide a way to create columns of text. Use of tables vs frames is recommended for helping to make your web site ADA-compliant.
Tag On clothes, tags usually indicate the brand, size of the garment, fabrics used, and the washing instructions. In Web pages, tags indicate what should be displayed on the screen when the page loads. Tags are the basic formatting tool used in HTML (hypertext markup language) and other markup languages, such as XML. For example, to create a table on a Web page, the tag is used. The data that should be inside the table follows the
tag, and the table is closed with a
tag. If you want something to show up in bold on a Web page, you would use the bold tag. For example, the line: This site is the best website ever! would show up as: This site is the best website ever! Since there is often a need to format content within more general tags, the tags can be "nested," meaning one tag can enclose one or more other tags. For example: This is the Times font, and this is in italics. Pretty exciting, huh? would should up as: This is the Times font, and this is in italics. Pretty exciting, huh? Tags are a fundemental part of HTML and they are pretty simple to understand.
Tamper To deliberately alter a system's logic, data, or control information to cause the system to perform unauthorized functions or services.
Tape Drive This is a removable storage device mainly used for backing up data. It is similar to a Zip Drive, but instead of Zip disks, it uses small tapes. The drive acts like a tape recorder, reading data from the computer and writing it onto the tape. Since tape drives have to scan through lots of tape to read small amounts of scattered data, they are not practical for most storage purposes. That is why they are used almost exclusively for data backup. The benefit of tape drives is that they typically have large capacities for storing data, for a lower cost than hard drives similar in size. Also, multiple tapes can be used to make incremental backups (daily, weekly, monthly, etc.), which is much cheaper than using multiple hard drives.
tar (file format) In computing, tar (derived from tape archive and commonly referred to as "tarball") is both a file format (in the form of a type of archive bitstream) and the name of a program used to handle such files. The format was created in the early days of Unix and standardized by POSIX.1-1988 and later POSIX.1-2001. Initially developed to be written directly to sequential I/O devices for tape backup purposes, it is now commonly used to collect many files into one larger file for distribution or archiving, while preserving file system information such as user and group permissions, dates, and directory structures.
Target Disk Mode Target disk mode is a way of booting a Macintosh computer so that it acts as an external hard drive on another computer. When a Mac is booted in target disk mode, the typical boot sequence is bypassed and the operating system is not loaded. Instead, the computer's internal and external hard drives are simply mounted on a connected computer. Target disk mode can be used to manually transfer files between two machines or to copy data from one computer to another using Apple's Migration Assistant. In order for target disk mode (TDM) to work, two Macintosh computers must be attached to each other via a Firewire cable. One computer should be on and the computer designated for TDM should be off. To boot into target disk mode, hold the "T" key on the keyboard immediately after turning on or restarting the computer. After a few seconds, the screen should display the Firewire icon, which will move around the screen as long as the machine is in target disk mode. You should then see the hard drive(s) of the computer in TDM appear on the Desktop of the connected computer. Booting a computer in target disk mode makes it easy to transfer files between two machines. Since the hard drives of the computer in TDM automatically mount on the other Mac's desktop, you can simply drag and drop files between them. Also, the computer in target disk mode is not seen as a boot disk, so you don't have to worry about file permissions. You can also run more comprehensive disk diagnostics and repairs. Just be sure not to remove or copy over any important system files on the TDM hard drive(s), since there are no safeguards to protect you from doing so. Since the hard drives of the TDM machine are mounted on the connected computer, you should make sure to unmount or "eject" the hard drives before you turn off the computer. This can be done by selecting the hard drive on the desktop and choosing "Eject" from the File menu. Once the hard drives are ejected, you can safely turn off the TDM computer. When you turn on the computer again, it should boot normally (as long as you don't hold down the "T" key). Any files you copied to the computer's hard drives should appear in the directories you copied them to.
Task Bar The task bar was introduced with Windows 95 and has been part of every version of Windows since then. It is the bar that spans the bottom of the screen and contains the Start button on the left side and the systray on the right. The task bar also includes the current time on the far right side and can hold shortcuts to programs directly to the right of the Start button. Most of the task bar, however, contains shortcuts to open windows. Whenever you open a program or window, it shows up in the task bar. So if you have Internet Explorer and Microsoft Word open, there will be at least two items in the middle area of the task bar. Since each window gets its own location in the task bar, if there are two Microsoft Word documents open and three Internet Explorer windows open, there will be a total of five items in the task bar. When you click on a window title in the task bar, that window will become active and show up in front of other open windows. You can also cycle through the task bar items by holding the Alt key and pressing Tab a few times.
TB 1. Abbreviation for terabyte, a unit of storage. 2. Chat abbreviation for: Text Back. This abbreviation simply asks for a text response and in essence is a way of texting "please respond".
TBD 1. To Be Done. 2. To Be Determined. 3. Technical Background Document. 4. To Be Decided. 5. To Be Developed.
Tcl Tool Command Language. A scripting language originating from Unix. Tcl can be extended by users and is suited for creating GUIs, and other tools. It can be used in mixed environments, including Windows, Mac and Unix platforms. See also Tcl/Tk.
Tcl/Tk Tool Command Language/Tool Kit. Tcl (Tool Command Language) with a set of graphical user components (originally developed as a Tcl extension) which has collectively become known as Tcl/Tk.
TCP Transmission Control Protocol. Connection-Oriented protocol for establishing a connection between two computers and for managing the delivery of data packets between the those computers. TCP is often used in conjunction with IP, which it is referred to as TCP/IP.
TCP Fingerprinting TCP fingerprinting is the user of odd packet header combinations to determine a remote operating system.
TCP Full Open Scan TCP Full Open scans check each port by performing a full three-way handshake on each port to determine if it was open.
TCP Half Open Scan TCP Half Open scans work by performing the first half of a three-way handshake to determine if a port is open.
TCP Wrapper A software package which can be used to restrict access to certain network services based on the source of the connection; a simple tool to monitor and control incoming network traffic.
TCP/IP Transmission Control Protocol/Internet Protocol. Transmission Control Protocol (TCP) used in conjunction with Internet Protocol (IP). cf CAT5, CAT5e, CAT6.
TCPDump TCPDump is a freeware protocol analyzer for Unix that can monitor network traffic on a wire.
Tebibyte A tebibyte is a unit of data storage that equals 2 to the 40th power, or 1,099,511,627,776 bytes. While a terabyte can be estimated as 10^12 or 1,000,000,000,000 bytes, a tebibyte is exactly 1,099,511,627,776 bytes. This is to avoid the ambiguity associated with the size of terabytes. A tebibyte is 1,024 gibibytes and precedes the pebibyte unit of measurement. For a list of other units of measurements, view this Help Center article. Abbreviation: TiB
Technology Refresh echnology Refresh (sometimes abbreviated to simply TR) is the periodic replacement of equipment to ensure continuing reliability of equipment and/or improved speed and capacity. cf evergreening, technology replacement.
Technology Replacement The policy for the periodic replacement of equipment to ensure the lowest cost of replacement technology that continuously satisfies the speed and capacity requirements over the life of the replacement. See also "Technology Refresh" and "evergreening".
Technology Services Technology services are services that make use of modern technology. Examples include Internet service providers (ISPs), Web hosts, and technical support companies. Since many technology services are related to information technology, they are sometimes called "information technology services," or ITS. However, other services like graphic design, audio/video production, and scientific engineering also fall under the scope of technology services. Therefore, while technology services are often related to IT, they may be associated with other forms of technology as well.
Telecom Refers to the industry and hardware involved with telephones and the transmission of voice data.
Telecommunications Telecommunications is the transmission of analog or digital signals over a long distance. This includes telephone calls, radio and television broadcasts, and data transfers over the Internet. Thanks to telecommunications, people can communicate instantly regardless of where they are located. The term "telecom" may also refer to a telecommunications company.
Telnet The command and program used to login from one Internet siteto another. The telnet command/program gets you to the login: prompt of another host.
TEMP File TEMP File A temporary file. This may be written as "TEMP file" or "temp file", case is not significant other than that TEMP is a system variable that indicates the folder in which temporary files should be generated. Temporary files are generated by applications and should be deleted automatically by the application that created them when they are no longer required. Unfortunately this frequently does not happen so temporary files can tend to build up over time. Temporary files can be deleted if they are no longer in use. Temporary files are commonly denoted by the file extension ".tmp" (or less commonly ".$$$") but this is not always the case. They are typically created in a directory designated as a temporary directory (meaning that the files in the directory are temporary files not that the directory itself is temporary), but some applications may create temporary files elsewhere.
Template A template is a file that serves as a starting point for a new document. When you open a template, it is pre-formatted in some way. For example, you might use template in Microsoft Word that is formatted as a business letter. The template would likely have a space for your name and address in the upper left corner, an area for the recipient's address a little below that on the left site, an area for the message body below that, and a spot for your signature at the bottom. When you save a file created with a template, you are usually prompted to save a copy of the file, so that you don't save over the template. Templates can either come with a program or be created by the user. Most major programs support templates, so if you find yourself creating similar documents over and over again, it might be a good idea to save one of them as a template. Then you won't have to format your documents each time you want to make a new one. Just open the template and start from there.
Temporary File A file which is generated by an application on a temporary basis and which the application should delete after use. Temporary files are generated by applications and should be deleted automatically by the application that created them when they are no longer required - unfortunately this frequently does not happen so temporary files can tend to build up over time. Temporary files can be deleted if they are no longer in use. Temporary files are commonly denoted by the file extension ".tmp" (or .$$$), but this is not always the case. They typically are created in a directory designated as a temporary directory (meaning that the files in the directory are temporary files not that the directory itself is temporary), but some applications may create temporary files elsewhere. Temporary files are often abbreviated to simply Temp file or TMP file.
Terabyte Unit of storage. Often abbreviated to TB. 1 terabyte = 2 to the fortieth (240) bytes = 1,099,511,627,776 bytes = 1024 gigabytes. See also petabyte.
Terminal 1. End point. For example the end point on a journey would be its terminal. Similarly the end point on a line (or polyline) would be the terminal point. 2. An electronic input/output device for communicating with a computer. Normally consisting of at least a keyboard and monitor. 3. Deadly. 4. An electrical connection point, such as on a circuit board.
Terminal Adapter An electronic device that interfaces a PC with a host computer via an ISDN phone line. They are often called "ISDN modems"; however, because they are digital, Terminal Adapters are not modems at all. See Also: Modem
Terminal Server A special purpose computer that has places to plug in many modemson one side, and a connection to a LAN or host machine onthe other side. Thus the terminal server does the work of answering the calls and passes the connections on to the appropriate node. Most terminal servers can provide PPP or SLIP services if connected to the Internet.
Text Editor A text editor is any word processing program that you can use to type and edit text. Hey, they don't call it a text editor for nothing... Word Pad and NotePad for Windows and SimpleText and TextEdit for the Mac are common text editors. Larger programs such as Microsoft Word and Word Perfect are also text editors, but they have many more features. You can actually write HTML code and create HTML pages with a simple text editor, as long as you know the correct HTML syntax.
Thermal Compound A paste that is applied between a microprocessor and heatsink. This paste fills in any tiny gaps that may be present on the visibly flat surfaces of the microprocessor package and heatsink. Without thermal compound cooling may be less efficient, as the heatsink and microprocessor package may have air gaps between them. Thermal compound has much more efficient heat exchange properties than air.
Thermal Paper A type of paper that displays a mark on it when heat is applied. Some older printers and fax machines used thermal paper, as it allowed for a very cheap printing mechanism.
Thermal Paste Synonymous with thermal compound. A paste that is applied between a microprocessor and heatsink. This paste fills in any tiny gaps that may be present on the visibly flat surfaces of the microprocessor package and heatsink. Without thermal compound cooling may be less efficient, as the heatsink and microprocessor package may have air gaps between them. Thermal compound has much more efficient heat exchange properties than air.
Thermal Tape Like thermal compound, thermal tape fits between a microprocessor package and heatsink and gives greater heat conductivity than air. Thermal tape is typically less efficient than thermal compound.
ThickNet The type of cabling on which 10Base5 Ethernet runs. It can transfer data at up to 10Mbps using the 10Base5 Ethernet standard. It is thicker than 10Base2 cabling, and thus the name.
Thin Client 1. A client/server application that is designed to minimize the amount of data (including the application itself) that needs to be transferred from the server to the client. Thin client applications are therefore small and perform most of the work on the server. cf Fat Client. 2. When applied to a computer rather than an application it refers to a client computer which is intended only to be used as a network client with no local storage and minimal processing capability. A thin client computer runs applications (such as word-processing, internet browser etc) on the server, using the thin client only as a display device. Thin client computers include network computers and X-terminals
ThinNet This refers to the type of cabling on which 10Base2 Ethernet runs. It can transfer data at up to 10Mbps using the 10Base2 Ethernet standard. It is thinner than 10Base5 cabling.
Thread An ongoing message-based conversation on a single subject. See Also: Mailing List, Newsgroup, Posting
Threat A potential for violation of security, which exists when there is a circumstance, capability, action, or event that could breach security and cause harm.
Threat Assessment A threat assessment is the identification of types of threats that an organization might be exposed to.
Threat Model A threat model is used to describe a given threat and the harm it could to do a system if it has a vulnerability.
Threat Vector The method a threat uses to get to the target.
Throughput Throughput refers to how much data can be transferred from one location to another in a given amount of time. It is used to measure the performance of hard drives and RAM, as well as Internet and network connections. For example, a hard drive that has a maximum transfer rate of 100 Mbps has twice the throughput of a drive that can only transfer data at 50 Mbps. Similarly, a 54 Mbps wireless connection has roughly 5 times as much throughput as a 11 Mbps connection. However, the actual data transfer speed may be limited by other factors such as the Internet connection speed and other network traffic. Therefore, it is good to remember that the maximum throughput of a device or network may be significantly higher than the actual throughput achieved in everyday use.
TIA Chat abbreviation: Thanks In Advance. Sometimes used in newsgroup postings where someone asks a question of the newsgroup, and ends it with the polite comment "TIA" ("Thanks In Advance").
TIFF Tagged Image File Format. A common image file format developed by Adobe. TIFF files are usually identified with a ".tif" or ".tiff" file extension.
Tiger This ferocious cat is the code name for Mac OS X 10.4, released April 29, 2005. Tiger follows a list of other felines in the Mac OS X lineup, including Panther (10.3), Jaguar (10.2), Puma (10.1), and Cheetah (10.0). Apple originally used the cat names as internal names for the operating system development, but actually started to market the names with the release of Jaguar. According to Apple, Tiger includes over 200 improvements from Mac OS X 10.3. A few of the most notable additions include an enhanced search feature called "Spotlight," an internal scripting program called "Automator," and quick information access via widgets from the new "Dashboard." Mac OS X 10.4 Tiger is a feature-rich operating system that some may consider as a serious alternative to Windows.
Time to Live A value in an Internet Protocol packet that tells a network router whether or not the packet has been in the network too long and should be discarded.
Time Zone Time Zone A North-South strip along the surface of the Earth which uses the same time standard, where notionally at 12 noon the sun is at its highest point in the sky. The Earth is divided into 24 time zones and within each time zone the same time standard is used (i.e. all the clocks in a given time zone should agree). Each time zone is roughly 15 degrees wide, but there are some variations because time zones are often bounded by country or administrative borders and it is often easier to follow these borders than the strict 15 degree boundary. Time zones are defined by the number of hours difference from UTC: UTC Offset Abbreviation Full Name Used Where UTC - 12 Eniwetok, Kwajalein UTC - 11 Midway Island, Somoa UTC - 10 Hawaii-Aleutian Standard Time Hawaii UTC - 9 AKST Alaska Standard Time Alaska UTC - 8 AKDT Alaska Daylight Time Alaska UTC - 8 PST Pacific Standard Time West coast of America and Canada UTC - 7 Arizona UTC - 7 Mountain Time America and Canada UTC - 6 Central America, Mexico City UTC - 6 CST Central Standard Time America and Canada UTC - 5 Bogota, Lima, Quito, East Indiana UTC - 5 EST Eastern Standard Time East coast of America and Canada UTC - 4 Atlantic Time Canada UTC - 4 Caracas, La Paz, Santiago UTC - 3 Newfoundland, Brasilia, Buenos Aires, Georgetown, Greenland UTC - 2 Mid-Atlantic UTC -1 Azores, Cape Verde Islands UTC UTC Coordinated Universal Time London UTC GMT Greenwich Meridian Time London UTC London, Casablanca, Monrovia UTC + 1 BST British Summer Time London UTC + 1 Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna, Belgrade, Bratislava, Budapest, Ljubljana, Prague, Brussels, Copenhagen, Madrid, Paris, Sarajevo, Skopje, Sofija, Vilnius, Warsaw, Zagreb, West Central Africa UTC + 2 Athens, Istanbul, Minsk, Bucharest, Cairo, Harare, Pretoria, Helsinki, Riga, Tallinn, Jerusalem UTC + 3 Baghdad, Kuwait, Riyadh, Moscow, St. Petersburg, Volgograd, Nairobi UTC + 4 Abu Dhabi, Muscat, Baku, Tbilisi, Yerevan UTC + 5 Ekaterinburg, Islamabad, Karachi, Tashkent UTC + 6 Almaty, Novosibirsk, Astana, Dhaka UTC + 7 Bangkok, Hanoi, Jakarta, Krasnoyarsk UTC + 8 Beijing, Chongqing, Hong Kong, Urumqi, Irkutsk, Ulaan Bataar, Kuala Lumpur, Singapore, Perth, Taipei UTC + 9 Osaka, Sapporo, Tokyo, Seoul, Yakutsk UTC + 10 Brisbane, Canberra, Melbourne, Sydney, Guam, Port Moresby, Hobart, Vladivostok UTC + 11 Magadan, Solomon Islands, New Caledonia UTC + 12 Auckland, Wellington, Fiji, Kamchatka, Marshall Islands UTC + 13 Muku'alofa As a further complication some countries observe daylight saving, which means that their local time is adjusted by one or two hours at certain times of the year to make best use of the available daylight.
Tiny Fragment Attack With many IP implementations it is possible to impose an unusually small fragment size on outgoing packets. If the fragment size is made small enough to force some of a TCP packet's TCP header fields into the second fragment, filter rules that specify patterns for those fields will not match. If the filtering implementation does not enforce a minimum fragment size, a disallowed packet might be passed because it didn't hit a match in the filter. STD 5, RFC 791 states: Every Internet module must be able to forward a datagram of 68 octets without further fragmentation. This is because an Internet header may be up to 60 octets, and the minimum fragment is 8 octets.
TITLE The official title of a document from the "meta" field called title. The text of this meta title field may or may not also occur in the visible body of the document. It is what appears in the top bar of the window when you display the document and it is the title that appears in search engine results. The "meta" field called title is not mandatory in HTML coding. Sometimes you retrieve a document with "No Title" as its supposed title; this is caused when the meta-title field is left blank. In Alta Vista and some other search tools, title: search also matches on the "meta" field, which contains document descriptors not displayed on the Web. See also LIMITING TO A FIELD.
Title Bar A title bar is the section at the top of a window that contains the name or description of the window. Nearly all windows displayed on your computer have a title bar. Therefore, if several windows are tiled across the screen at one time, a user can identify each window by just glancing at the title bar. Windows makes this even easier by placing the information from each window's title bar in the Task Bar. Mac OS X displays the title bar information in the middle of each window when the Expos? function is active. The title bar is a standard user interface GUI convention used by many applications, as well as the operating system itself. For example, in a Web browser window, the title bar typically is the title of the current Web page. In a word processor window, the title bar is usually the name of the document itself. If the document has not been named or saved yet, the title bar may read "Document 1" or "Untitled." When folders are opened on the Desktop, the folder window typically displays the name of the active folder in the title bar. In Windows, the title bar can also be set to display the full path to the folder's location by selecting "Folder Options" in the Tools menu. While the title bar serves as an identifier for each window, it also has another important function. By clicking and dragging the title bar, you can move a window to another location on the screen. This is important to know, since the title bar is often the only place you can click to move the window. Also, double-clicking the title bar will minimize the window, placing the window in the Task Bar (Windows) or the Dock (Mac OS X).
TLD Top Level Domain) The last (right-hand) part of a complete Domain Name. For example in the domain name www.matisse.net ".net" is the Top Level Domain. There are a large number of TLD's, for example .biz, .com, .edu, .gov, .info, .int, .mil, .net, .org, and a collection of two-letter TLD's corresponding to the standard two-letter country codes, for example, .us, .ca, .jp, etc. See also: Domain Name
TLS 1. Transport Layer Security. A protocol which is intended to enhance SSL.
TM 1. Trade Mark. Often represented as ™. The trademark symbol shows that a name is used by a business to exclusively identify itself or a specific product. Trade marks do not need to be registered, but under UK law (and the law in this respect may vary from country to country) it is the first person who registers the trademark who can legally prevent others from using it.
TMP File A temporary file. Temporary files are generated by applications and should be deleted automatically by the application that created them when they are no longer required - unfortunately this frequently does not happen so temporary files can tend to build up over time. Temporary files can be deleted if they are no longer in use. Temporary files are commonly denoted by the file extension ".tmp", but this is not always the case. They typically are created in a directory designated as a temporary directory (meaning that the files in the directory are temporary files not that the directory itself is temporary), but some applications may create temporary files elsewhere.
TOC Table of Contents. A list of section headings for a document, normally providing page numbers.
Token A token is a group of bits that are transferred between computers on a token-ring network. Whichever computer has the token can send data to the other systems on the network. This ensures that only one computer can send data at a time. A token may also refer to a network security card, also known as a hard token.
Token Ring A token ring network is a local area network in which all computers are connected in a ring or star topology and a binary digit or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time.
Token-Based Access Control Token based access control associates a list of objects and their privileges with each user. (The opposite of list based.)
Token-Based Devices A token-based device is triggered by the time of day, so every minute the password changes, requiring the user to have the token with them when they log in.
Tomcat a web server from the Jakarta Project
Tooltip As computer users, we have become accustomed to icons that represent files, folders, programs, and other objects on the computer. Many software programs also use icons to represent tools, which are often found in the program's toolbar. While these icons can save screen space and make the program's interface more attractive, it can sometimes be difficult to tell what all the tool icons mean. While some tool icons are obvious (such as a printer icon to print and a scissors icon to cut a text selection), others are a bit more ambiguous. For this reason, programs often include tooltips that explain what each tool icon represents. Tooltips are displayed when you roll over an icon with the cursor. It may take a second or two to display the tooltip, but when it does appear, it usually is a small box with a yellow background explaining what the icon represents. For example, in Microsoft Word, when you roll over the disk icon, the tooltip "Save" appears. This means clicking on the disk icon will save your document. In Photoshop, when you roll over the wand icon, the text "Magic Wand Tool (W)" appears. This indicates that clicking the the wand icon or pressing the W key will activate the magic wand selection tool. Not all programs incorporate tooltips, but most modern programs include them as part of a user-friendly interface. Operating systems also support them in different ways. For example, Mac OS X will show the full text of a long filename when you place the cursor over the filename. Windows includes tooltips for the systray icons and also tells you information about each file and folder you place the cursor over. If you drag your cursor over different icons on your computer, you may find tooltips you never knew were there!
Topology The geometric arrangement of a computer system. Common topologies include a bus, star, and ring. The specific physical, i.e., real, or logical, i.e., virtual, arrangement of the elements of a network. Note 1: Two networks have the same topology if the connection configuration is the same, although the networks may differ in physical interconnections, distances between nodes, transmission rates, and/or signal types. Note 2: The common types of network topology are illustrated
Torrent A torrent is a file sent via the BitTorrent protocol. It can be just about any type of file, such as a movie, song, game, or application. During the transmission, the file is incomplete and therefore is referred to as a torrent. Torrent downloads that have been paused or stopped cannot be opened as regular files, since they do not contain all the necessary data. However, they can often be resumed using a BitTorrent client, as long as the file is available from another server. Torrents are different from regular downloads in that they are usually downloaded from more than one server at a time. The BitTorrent protocol uses multiple computers to transfer a single file, thereby reducing the bandwidth required by each server. When a torrent download is started, the BitTorrent system locates multiple computers with the file and downloads different parts of the file from each computer. Likewise, when sending a torrent, the server may send the file to multiple computers before it reaches the recipient. The result is a lower average bandwidth usage, which speeds up file transfers. File Extension: .TORRENT
Torx A type of indent in a screw head that looks like a 6-pointed star. Compaq used torx screws for all of its computer equipment at one point. Torx screws are also used in some automotive applications for body trim that should not be easily removed, such as to hold in the headlights on a ‘79 Chevy Malibu. Because a Torx driver is rarer than a Phillips-head or flat-head screwdriver, Torx screws are used as a simple security method.
TOS 1. Terms Of Service. Sometimes also referred to as T&C 2. Top Of Stack. 3. The Other Service. 4. Abbreviation for TOSLink. 5. Type of Service. TOS refers to the Type of Service field in a ping generated ICMP packet.
Total Cost of Ownership (TCO) This phrase was coined by the creators of the Network Computer (NC) to describe the benefits of using a system that is more mainframe and less client/server. Their logic states that NCs, although they may cost the same up front as cheap PCs, have a lower TCO than a network built on PCs.
TOU Terms Of Use. More commonly referred to as T&C
Touchpad A pad that is electrically sensitive to touch, often used as the pointing device in laptops. You can also tap on it for clicks, but some people find that annoying if they bump the pad while typing.
Tower Case An improvement to the standard desktop case, a tower case is flipped 90 degrees to accommodate more inside and to make it more convenient by allowing the case to be placed on the floor instead of on the desk.
TR 1. Abbreviation for Transmit/Receive. 2. Abbreviation for Technology Refresh. 3. Abbreviation for Token-Ring. 4. Abbreviation for Top-Right
Traceroute When computers communicate over the Internet, there are often many connections made along the way. This is because the Internet is made up of a network of networks, and two different computers may be on two separate networks in different parts of the world. Therefore, if a computer is to communicate with another system on the Internet, it must send data through a series of small networks, eventually getting to the Internet backbone, and then again traveling to a smaller network where the destination computer resides. These individual network connections, called "hops," typically go unnoticed by the average user. After all, why bother tracking all the various connections when you are only interested in communicating with the destination computer? However, if a connection cannot be made or is taking a unusually long time, tracing the path of connections along the way can prove to be helpful. This is exactly what the traceroute command does. Traceroute is a TCP/IP utility that allows a user to trace a network connection from one location to another, recording every hop along the way. The command can be run from a Unix or DOS command line by typing tracert [domain name], where [domain name] is either the domain name or the IP address of the system you are trying to reach. A traceroute can also be done using various networking utilities, such as Apple's Network Utility for Mac OS X. When a traceroute is run, it returns a list of network hops and displays the host name and IP address of each connection. It also returns the amount of time it took for each connection to take place (usually in milliseconds). This shows if there were any delays in establishing the connection. Therefore, if a network connection is slow or unresponsive, a traceroute can often explain why the problem exists and also show the location of the problem.
Traceroute (Tracert) A command that displays PING results for each router encountered between a source and a destination TCP/IP address. Traceroute is useful for getting some information along the entire path between two TCP/IP addresses. Firewalls or other security measures that block PING traffic also block traceroutes. The command itself is typed “tracert” on the command line of most operating systems.
Tracert (Traceroute) A command that displays PING results for each router encountered between a source and a destination TCP/IP address. Traceroute is useful for getting some information along the entire path between two TCP/IP addresses. Firewalls or other security measures that block PING traffic also block traceroutes. The command itself is typed “tracert” on the command line of most operating systems.
Trackback Trackback is a protocol for notifying websites that other websites have linked to it. When a trackback link is added to a Web page, the linked website is notified that the link has been added. However, both websites must support the trackback protocol in order for the system to work. For this reason, trackback is most commonly used by blogging websites to share links and responses to blog entries.
Trackball A trackball is an input device that has a ball which is held in a socket and can be rolled in any direction. Most trackballs perform the same functions as a mouse and are used primarily to control the cursor on a computer screen. However, unlike a mouse, a trackball device remains stationary when the user move the ball. This makes trackballs ideal for areas with limited space.
Transactions Per Minute (TPM) The amount of database transactions a server can do in a minute’s time. This method of measurement is often used to compare high-powered database servers with multiple processors. Often the ratio of money per transactions is used to show the cost-effectiveness of a particular server.
transistor One of the most important inventions in history, the transistor can be found in nearly every common electronic device manufactured today--radios, TV sets, cellular phones, computers, and so on. Originally created in the late 1940s by Bell Labs, the transistor was hailed as a smaller, less-expensive, and cooler-running replacement for the vacuum tubes then commonly used to amplify current in electronic devices. Today, millions of transistors are often packed into silicon chips to create the processors used in modern computers.
Transmission Control Protocol (TCP) The part of the TCP/IP suite of protocols that is responsible for forming data connections between nodes that are reliable, as opposed to UDP, or IP, which TCP is based on, and which is by default connectionless and potentially unreliable.
Transmission Control Protocol/Internet Protocol (TCP/IP) The TCP/IP suite first saw use on the original Department of Defense Internet in 1983. Its first implementation was amazingly successful, and it is still THE protocol of the Internet. In fact, it has grown even more, and is being used in private networks around the world. TCP/IP is a suite of communications protocols that allows communication between groups of dissimilar computer systems from a variety of vendors. It scales better than NetBEUI because NetBEUI is not routable, and beat out IPX/SPX as it was easier to route than that once-dominant protocol.
Transport Layer Security (TLS) A protocol that ensures privacy between communicating applications and their users on the Internet. When a server and client communicate, TLS ensures that no third party may eavesdrop or tamper with any message. TLS is the successor to the Secure Sockets Layer.
Trawl To search for, specifically to search through a large amount of information for, such as trawling (i.e. searching) the web for information.
Tree A means of organizing data that starts with a single node, or data element, that has any number of child elements. Each of these child elements or nodes can also have its own child elements. Trees are an important part of understanding programming and data structures.
Triple DES Encryption A form of DES encryption that uses three separate 56-bit keys to encrypt and decrypt messages. This basically compounds the number of possible key combinations (72 quadrillion) three times, and makes it even harder to crack an encrypted message.
Triple-Wrapped S/MIME usage: data that has been signed with a digital signature, and then encrypted, and then signed again.
Trivial File Transfer Protocol (TFTP) A network transfer protocol that allows you to connect to a device and download code onto it. For example, it can be used to shove boot code onto a diskless workstation, or connect and download firmware updates to networking devices.
Trojan A harmful application (or routine) that hides it malicious activities by masquerading as a more useful, harmless and desirable application. In many respects a Trojan is like a virus, except that it does not provide a means to copy itself. A Trojan instead relies upon the fact that it masquerades as something useful that people will recommend or copy-on the application. Trojan's are often found in software that is freeware, although it must be stressed that most freeware is free of viruses and Trojans. Anti-virus applications will typically scan for many known Trojans. Anti-virus writers tend to classify a Trojan as one of the following depending on what the Trojan does: Trojan Downloader - downloads and installs new software on the computer. Trojan Dropper - installs new software on the computer. Trojan Proxy - turns the computer into a proxy server providing anonymous access to the internet for the Trojan writer. Trojan PSW - password stealer, hunts the computer for stored usernames and passwords and forwards these to the Trojan writer. Trojan Spy - any form of spyware application, such as keyloggers, password stealers etc. Trojans get their name from the classical Greek story of the Trojan horse, used in the Trojan war. The Trojan horse was a large wooden horse left as a gift from the Greeks to the Trojans, the Greeks then sailed away (apparently admitting defeat). The Trojans moved the horse inside their city walls and then celebrated their apparent victory. Unfortunately for the Trojans the Trojan Horse contains a number of Greek soldiers who then killed the guards and let the remainder of the Greek army into the city who then sacked Troy. A Trojan is also known as a Trojan horse.
Trojan Horse A harmful application (or routine) that hides it malicious activities by masquerading as a more useful, harmless and desirable application. A Trojan horse is also referred to simply as a "Trojan", see Trojan for details.
Troubleshooting Troubleshooting is the process or identifying and fixing problems. Computer troubleshooting may involve hardware or software and can sometimes involve both at the same time. The basic process of troubleshooting is to check the most general possible problems first, and then gradually check for more specific problems. This provides a logical approach to problem solving and can apply to multiple types of products.
True Color The name given to 32-bit, 16.7 million color representation.
True Parity This term has come about with the advent of logical parity memory. It simply means that the parity memory actually does something useful instead of just issuing positives over and over.
TrueType This is a font standard developed by Apple and used in Mac OS version 7. Later, Apple licensed the technology to Microsoft, which used it in Windows 3.1 and continues to use it today. However, Apple and Microsoft TrueType fonts are not compatible.
Truncate To truncate something is to shorten it, or cut part of it off. In computer science, the term is often used in reference to data types or variables, such as floating point numbers and strings. For example, a function may truncate the decimal portion of a floating point number to make it an integer. If the number 3.875 is truncated, it becomes 3. Note that this is different than if the number had been rounded to the nearest integer, which would be 4. Strings may also be truncated, which can be useful if a string exceeds the maximum character limit for a certain application. Several programming languages use the function trunc() to truncate a variable. PHP uses strlen() to truncate a string to a set limit of characters.
TRUNCATION In a search, the ability to enter the first part of a keyword, insert a symbol (usually *), and accept any variant spellings or word endings, from the occurrence of the symbol forward. (E.g., femini* retrieves feminine, feminism, feminism, etc.)
Trunking Trunking is connecting switched together so that they can share VLAN information between them.
Trust Trust determine which permissions and what actions other systems or users can perform on remote machines.
Trusted Ports Trusted ports are ports below number 1024 usually allowed to be opened by the root user.
Tunnel A communication channel created in a computer network by encapsulating a communication protocol's data packets in (on top of) a second protocol that normally would be carried above, or at the same layer as, the first one. Most often, a tunnel is a logical point-to-point link - i.e., an OSI layer 2 connection - created by encapsulating the layer 2 protocol in a transport protocol (such as TCP), in a network or inter-network layer protocol (such as IP), or in another link layer protocol. Tunneling can move data between computers that use a protocol not supported by the network connecting them.
Tunneling The term "tunneling" probably brings to mind images of digging tunnels underground, perhaps for a subway system, or for you more technically-minded, a fiber optic cable connection. In the virtual world of computers world, however, tunneling refers to a protocol in which one protocol is encapsulated within another. Tunneling protocols are often used for establishing various types of connections over common protocols, such as HTTP. For example, a peer-to-peer (P2P) file sharing program may mask data as HTTP to allow the data to be transferred through a firewall. Since most firewalls allow HTTP (port 80) connections, the connection would likely be allowed, since this is the same port that the Web uses. If the program used its own protocol and port number, the connection may be blocked. Tunneling can also be used to establish secure connections through protocols that are typically not secure. For example, the point-to-point tunneling protocol (PPTP) establishes a secure connection over a standard PPP connection, and can used to create a virtual private network (or VPN) between two remote locations. PPTP allows a user to "tunnel" to another location with a secure password-protected connection using the standard or PPP protocol.
Turnkey This usually refers to a server or a complex system that can basically be shipped from the manufacturer, turned on, and work right away. Many VARs pride themselves on providing turnkey servers on which their customers don’t need to do any configuration. If you think of it in terms of an engine, a turnkey engine comes with all the parts and can be tossed into a car and work immediately. An engine that isn’t turnkey will need additional parts and integration before it will run.
Tutorial A computer tutorial is an interactive software program created as a learning tool. Tutorials help people learn new skills by using a step-by-step process that ensures the user is following along and comprehending the material. For example, a Web development tutorial may begin with instructions on how to create a basic Web page. This page might only include the words "Welcome to my website" on it and use the minimum HTML required in order for the page to load in a Web browser. Once the user is able to create a working Web page, the tutorial may explain how to add other features, such as styled text, table layouts, and images, to the page. Then the tutorial may provide instructions on how to publish the Web page to the Internet. Some software tutorials provide testing features to ensure comprehension of the material, while others may be simple walkthroughs of a software program. Tutorials can be used for both school and business purposes and are written for basic, intermediate, and advanced users. Even smart computer programmers use tutorials. Most software development programs include a tutorial for creating a "Hello World!" program, which is the most basic program that can be created with the software. Since tutorials offer a gradual approach to learning, they can be helpful to people at many different skill levels. If a computer programmer can benefit from a tutorial, just about anybody can.
TWAIN The TWAIN working group (www.twain.org) is a non-for-profit organisation which represents the imaging industry, whose purpose is to provide and foster a universal public standard which links applications and image acquisition devices. TWAIN is often loosely referred to as an interface standard for image acquisition devices.
Tweak When you modify a certain piece of hardware for better performance, it is often referred to as "tweaking" it. Overclocking the computer's CPU or changing jumper settings on the motherboard are common examples of hardware tweaking. Removing system limitations and adding plug-ins or extensions to a computer's operating system are types of software tweaking. Tweaking a computer is much like "tuning" a car (you know, the ones with the huge mufflers, big spoilers, and pimped out rims). It may increase performance, but is best left in the hands of the technically savvy. For example, overclocking your computer's processor may cause it to crash frequently, or worse yet, overheat and destroy the CPU. So, for most people, it is best to leave well enough alone.
twisted pair Telephone companies commonly run twisted pairs of copper wires to each customer household. The pairs consist of two insulated copper wires twisted into a spiral pattern. Although originally designed for plain old telephone service (POTS), these wires can carry data as well as voice. New services such as ISDN and ADSL also use twisted-pair copper connections. See also: ISDN, ADSL, POTS
two-factor authentication An extra level of security achieved using a security token device; users have a personal identification number (PIN) that identifies them as the owner of a particular token. The token displays a number which is entered following the PIN number to uniquely identify the owner to a particular network service. The identification number for each user is changed frequently, usually every few minutes.
TXT File A text file is one which holds just text with no document formatting information. They are the most basic type of file and so can be opened with any text editor or word processor. Also known as an "ASCII Text File" or "Plain Text File". A TXT file is often denoted by a file extension of ".txt", but there are many other file types which can also be classified as text files (for example a ".ini" file, which is normally an initialisation file, is normally a text file).
Typeface A typeface is a set of characters of the same design. These characters include letters, numbers, punctuation marks, and symbols. Some popular typefaces include Arial, Helvetica, Times, and Verdana. While most computers come with a few dozen typefaces installed, there are thousands of typefaces available. Because they are vector-based (not bitmaps), typefaces can be scaled very large and still look sharp. The term "typeface" is often confused with "font," which is a specific size and style of a typeface. For example, Verdana is a typeface, while Verdana 10 pt bold is a font. It's a small difference, but is good to know.