Glossary of Computer Terms starting with alphabet 'T'

TWAIN

It is a graphics and imaging standard that allows companies to make drivers for scanners and digital cameras. Nearly all scanners on the market today are TWAIN-compliant, meaning the way they interact with your computer is based on the TWAIN standard. 

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.

Twitter

Twitter is an online service that allows you to share updates with other users by answering one simple question: "What are you doing?"

In order to use Twitter, you must first sign up for a free account. Once you have created your account, you can post your own updates and view the updates others have posted. You can search for people to follow or you can let Twitter select random users. Once you have selected a number of users, their most recent posts, or "tweets," will show up on your Twitter home page. Likewise, your own latest tweets will show up on the home pages of people who have decided to follow you.

Twitter limits each tweet to 140 characters, which means there is no room for rambling. Of course, in this era of limited attention spans, 140 characters may be as much as other users want to read anyway. The character limit is also within the 160 character limit of SMS text messages. This is useful, since tweets can be sent to Twitter using mobile phones. To Twitter via your cell phone, you simply need to add your phone number in the "Devices" area of the Twitter Settings page.

Since most people have frequent access to a computer or cell phone, Twitter makes it possible to provide others with frequent updates about your life. Many people also use Twitter to blog about the news, politics, TV shows, or any other hot topic. Some people even use it to share their thoughts on lectures or sermons. So Twitter posts are certainly not limited to answering the question, "What are you doing?"

Twitter has become the next hot trend in social networking. While it is not as functional as Facebook or MySpace, Twitter's appeal lies within its simplicity. It allows friends, family, and complete strangers to stay connected through quick updates that only take a couple of seconds to write. Therefore, if you like to feel connected to others, but have limited time, Twitter might be just be for you.

While "Twitter" is a noun, in can also be used as a verb. For example, "He twitters at least five times a day." To learn more about Twitter or to sign up for an account, visit Twitter.com.

Tweet

For most of history, "tweet" has been the sound a bird makes. However, with the advent of Twitter, the word "tweet" has taken on a whole new meaning.

A tweet is an online posting, or "micro-blog" created by a Twitter user. The purpose of each tweet is to answer the question, "What are you doing?" However, tweets can contain any information you want to post, such as your plans for the weekend, your thoughts about a TV show, or even notes from a lecture. You can publish a tweet using a computer or a mobile phone. Once published, the tweet will appear on the Twitter home pages of all the users that are following you. Likewise, your Twitter home page will display the most recent tweets of the users that you are following.

Each tweet is limited to 140 characters or less. This limit makes it possible to show several tweets on one page without certain tweets taking up a lot more space than others. However, it also means that tweets must be brief, so you must choose your words wisely. Of course, there is no limit to how many tweets you can post, so if you really have a lot to say, you can publish several tweets in a row. After all, what better way to spend your time than to let the world know that you are at Starbucks, drinking a Frappuccino and reading the latest issue of TIME magazine. That is important information to share with the world.

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 usesstrlen() to truncate a string to a set limit of characters.

Troubleshooting

Troubleshooting is the process of diagnosing the source of a problem. It is used to fix problems with hardware, software, and many other products. The basic theory of troubleshooting is that you start with the most general (and often most obvious) possible problems, and then narrow it down to more specific issues.

Many product manuals have a "Troubleshooting" section in the back of the manual. This section contains a list of potential problems, which are often phrased in the form of a question. For example, if your your computer's monitor is not producing an image, you may be asked to answer the following troubleshooting questions:

1. Is the monitor plugged in to a power source?
2. Is the monitor turned on?
3. Is the monitor cable plugged into the computer?
4. Is the computer turned on?
5. Is the computer awake from sleep mode?

If the answers to all the above questions are Yes, there may be some additional questions such as:

1. Does your computer have a supporting video card?
2. Have you installed the necessary video card drivers?
3. Is the monitor resolution set properly?

Typically, each of these questions will be followed by specific advise, whether the answer is Yes or No. Sometimes, this advice is presented as a flowchart diagram. This means each question is followed by a series of other questions, depending on the answer. However, in many cases, only single solutions are provided for each question.

Troubleshooting is something we all have to do at some point, though some of us have to troubleshoot product problems more often than others. The good news is that, the more you do it, the more you learn and the better you get at fixing problems. Since many products have similar troubleshooting steps, you may find that after awhile, you don't even need the manual to find solutions to the problems you encounter.

Trojan Horse

In the computing world, Trojan horses are more than just a myth. They really exist and can cause damage to your computer. Trojan horses are software programs that masquerade as regular programs, such as games, disk utilities, and even antivirus programs. But if they are run, these programs can do malicious things to your computer.

For example, a Trojan horse might appear to be a computer game, but once you double-click it, the program starts writing over certain parts of your hard drive, corrupting your data. While this is certainly something you want to avoid, it is good to know that these malicious programs are only dangerous if they are given a chance to run. Also, most antivirus programs can catch Trojan horses when scanning for viruses. Unlike viruses, however, Trojan horses don't replicate themselves. Though it is possible for a Trojan horse to be attached to a virus file that spreads to multiple computers.

So as a general rule, don't open a program unless you know it is legitimate. This applies especially to e-mail attachments that are executable files. Even if you are pretty sure the attachment is OK, it is still a good idea to run it through your virus scan program (with the latest virus definitions) just to be safe. 

Trash

When you delete a file or folder on a Macintosh computer, it is stored in the Trash. In early versions of the Mac OS, the Trash was located on the desktop, but in Mac OS X, it is found in the Dock. The Trash icon is an empty trash bin when the Trash is empty and changes to a full trash bin when there are items in the Trash.

The Trash serves the same purpose as the Windows Recycle Bin. Items can be moved to the Trash by selecting them and dragging them to the Trash icon. You can also choose "Move to Trash" from the Finder's File menu or press Command-Delete after selecting one or more items. You may view items in the Trash by clicking the Trash icon in the Dock. Since the items stored in the Trash have not been permanently deleted, you can drag items out of the Trash if you wish to keep them.

Emptying the Trash

If you are sure you want to permanently delete the items in the Trash, you can press the "Empty" button in the Trash window or right-click anywhere within the window and select "Empty Trash." You can also empty the trash without even opening the Trash window by selecting "Empty Trash..." from the Finder menu. If you want to overwrite the deleted data so it cannot be recovered even with a data recovery utility, you can select "Secure Empty Trash..."

NOTE: If you wish to delete locked items that are stored in the Trash, hold the Option key while selecting "Empty Trash."

Transistor

A transistor is a basic electrical component that alters the flow of electrical current. Transistors are the building blocks of integrated circuits, such as computer processors, or CPUs. Modern CPUs contain millions of individual transistors that are microscopic in size.

Most transistors include three connection points, or terminals, which can connect to other transistors or electrical components. By modifying the current between the first and second terminals, the current between the second and third terminals is changed. This allows a transistor to act as a switch, which can turn a signal on or off. Since computers operate in binary, and a transistor's "on" or "off" state can represent a 1 or 0, transistors are suitable for performing mathematical calculations. A series of transistors may also be used as a logic gate when performing logical operations.

Transistors in computer processors often turn signals on or off. However, transistors can also change the amount of current being sent. For example, an audio amplifier may contain a series of transistors that are used to increase the signal flow. The increased signal generates an amplified sound output. Because of their low cost and high reliability, transistors have mostly replaced vacuum tubes for sound amplification purposes.

While early transistors were large enough to hold in your hand, modern transistors are so small they cannot be seen with the naked eye. In fact, CPU transistors, such as those used in Intel's Ivy Bridge processor, are separated by a distance of 22 nanometers. Considering one nanometer is one millionth of a millimeter, that is pretty small. This microscopic size allows chip manufacturers to fit hundreds of millions of transistors into a single processor.

Trackball

A trackball is an input device used to enter motion data into computers or other electronic devices. It serves the same purpose as a mouse, but is designed with a moveable ball on the top, which can be rolled in any direction. Instead of moving the whole device, you simply roll the moveable ball on top of the trackball unit with your hand to generate motion input.

Trackballs designed for computers generally serve as mouse replacements and are primarily used to move the cursor on the screen. Like mice, computer trackball devices also include buttons, which can serve as left-click and right-click buttons, and may also be used to enter other commands. While trackballs are most commonly used with computers, they may also be found in other electronics, such as arcade games, mixing boards, and self-serve kiosks. These devices often have trackballs that are larger than the ones used in computer input devices.

Besides the capability to be built into various devices, trackballs have a number of other advantages over mice. Some advantages include the small footprint (since they don't require a mousepad or large area to move the mouse), fingertip control (which may offer more accuracy), and improved ergonomics (since there is less strain on the wrist). Still, many people find trackballs harder to use than mice, since they feel less natural and may require practice to get used to. For this reason, the vast majority of computers include a mouse, rather than a trackball, as the default input device.

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.

Touchscreen

A touchscreen is a display that also serves as an input device. Some touchscreens require a proprietary pen for input, though most modern touchscreens detect human touch. Since touchscreen devices accept input directly through the screen, they do not require external input devices, such as mice and keyboards. This makes touchscreens ideal for computer kiosks, as well as portable devices, such as tablets and smartphones.

While a touchscreen may look like an ordinary display, the screen includes several extra layers that detect input. The first layer is a hard protective layer that protects the actual display and the touchscreen components. Beneath the protective layer is an electronic grid that detects input. Most modern touchscreens use capacitive material for this grid, in which the electrical charge changes wherever the screen is touched. Beneath the touchscreen layer is the LCD layer, which is used for the actual display.

While early touchscreens could only detect a single point of input at a time, modern touchscreens support "multi-touch" input. This technology, which was made popular by the original iPhone, enables the screen to detect multiple finger motions at once. For example, on some touchscreen devices, you can rotate an image by twisting three fingers in a clockwise or counterclockwise motion. Many touchscreen applications also allow you zoom in and out by spreading two fingers apart or pinching them together.

Thanks to multi-touch and other improvements in touchscreen technology, today's touchscreens are easier and more natural to use than they used to be. In fact, improved touchscreen technology has greatly contributed to the popularity of the iPad and other tablet PCs.

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

Toolbar

A toolbar is a set of icons or buttons that are part of a software program's interface or an open window. When it is part of a program's interface, the toolbar typically sits directly under the menu bar. For example, Adobe Photoshop includes a toolbar that allows you to adjust settings for each selected tool. If the paintbrush is selected, the toolbar will provide options to change the brush size, opacity, and flow. Microsoft Word has a toolbar with icons that allow you to open, save, and print documents, as well as change the font, text size, and style of the text. Like many programs, the Word toolbar can be customized by adding or deleting options. It can even be moved to different parts of the screen.

The toolbar can also reside within an open window. For example, Web browsers, such as Internet Explorer, include a toolbar in each open window. These toolbars have items such as Back and Forward buttons, a Home button, and an address field. Some browsers allow you to customize the items in toolbar by right-clicking within the toolbar and choosing "Customize..." or selecting "Customize Toolbar" from the browser preferences. Open windows on the desktop may have toolbars as well. For example, in Mac OS X, each window has Back and Forward buttons, View Options, a Get Info button, and a New Folder button. You can customize the Mac OS X window toolbars as well.

Toolbars serve as an always-available, easy-to-use interface for performing common functions. So if you haven't made use of your programs' toolbar options or customization features in the past, now is a good time to start!

Token

Besides those small shiny coins that allow you to play video games, there are three different types of tokens:

1. In networking, a token is a series of bits that circulate on a token-ring network. When one of the systems on the network has the "token," it can send information to the other computers. Since there is only one token for each token-ring network, only one computer can send data at a time.

2. In programming, a token is a single element of a programming language. There are five categories of tokens: 1) constants, 2) identifiers, 3) operators, 4) separators, and 5) reserved words. For example, the reserved words "new" and "function" are tokens of the JavaScript language. Operators, such as +, -, *, and /, are also tokens of nearly all programming languages.

3. In security systems, a hard token is small card that displays an identification code used to log into a network. When the card user enters the correct password, the card will display the current ID needed to log into the network. This adds an extra level of protection to the network because the IDs change every few minutes. Security tokens also come in software versions, called soft tokens.

Toggle Key

A toggle key toggles the input from a group of keys on a keyboard between two different input modes. The most common toggle key is Caps Lock, which toggles the letter keys between lowercase and uppercase mode. Some keyboards also have other toggle keys, such as Num Lock, Scroll Lock, and Insert. Below is a list of toggle keys and their functions.

• Caps Lock - capitalizes the input of all letter keys when turned on; may allow lowercase letters to be entered using the Shift key on some 
• keyboards; does not affect the number keys.


• Num Lock - ensures numbers are input from the numeric keypad rather than arrows or other commands; typically turned on by default; may also be used to change letter keys to numbers on laptop keyboards.


• Scroll Lock - causes the arrow keys to scroll through the contents of a window when turned on; allows users to scroll using the arrow keys rather then clicking on the scroll bar at the right side or bottom of a window; not supported by most modern operating systems.


• Insert - toggles between "insert mode" and "overtype mode" when entering text; insert mode is the default mode, which inserts characters wherever the cursor is located, while overtype mode overwrites characters as the user types; also not supported by most modern operating systems.
Unlike modifer keys, toggle keys are switched on or off each time they are pressed. Therefore, toggle keys do not need to be held down when pressing other keys. Some keyboards have lights on or near the toggle keys to let the user know if they are turned on or off. Some modern operating systems also display the status of toggle keys on the user's screen. For example, the software installed with Logitech keyboards on Macintosh computers displays a Caps Lock icon in the menu bar whenever Caps Lock is turned on.

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 Xdisplays the title bar information in the middle of each window when the Exposé function is active.

The title bar is a standard user interface GUIconvention used by many applications, as well as the operating system itself. For example, in aWeb 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).

TIFF

Stands for "Tagged Image File Format." It is graphics file format created in the 1980's to be the standard image format across multiple computer platforms. The TIFF format can handle color depths ranging from 1-bit to 24-bit. Since the original TIFF standard was introduced, people have been making many small improvements to the format, so there are now around 50 variations of the TIFF format. So much for a universal format. Recently, JPEG has become the most popular universal format, because of its small file size and Internet compatibility.

File extensions: .TIF, .TIFF

Thumbnail

A thumbnail image is a small image that represents a larger one. Thumbnails are often used to provide snapshots of several images in a single space. They are commonly used by digital photo organization programs as well as visual search engines.

The term "thumbnail" was originally used to describe physical images or drawings that were miniature in size (roughly the size of a human thumbnail). However, it is now widely used to describe digital images, which are displayed on a screen. Digital thumbnails are usually between 75x75 and 200x200 pixels in size. They can also have a rectangular aspect ratio, such as 150x100 pixels.

Since digital thumbnails represent a larger version of the same image, they also usually serve as a link to the larger image. For example, clicking a thumbnail on a Google Images search results page will open the page that includes the full size image. Similarly, double-clicking a thumbnail image in a photo browser will usually display the full size version.

Thumbnail images may also be referred to as "thumbs."

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.

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 (orVPN) 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.

TTL

Stands for "Time To Live." Pretty intense for a computer term, huh? It refers an aspect of the Internet Protocol. TTL is used when a "ping," or a request for a response, is sent to another computer, such as a server. The TTL represents the number of hops, or servers in different locations, the request can travel to before returning a failed attempt message.

Trackback

Trackback is a means of notifying a website that another website has linked to it. By linking to a trackback link, a webmaster can automatically inform the other website that he has added a link to one of site's pages. However, in order for the trackback system to work, both websites must support trackback. This is because the linking website needs to ping the linked website to let it know a link has been added.

Trackback was first implemented by Movable Type blogging and Web design software in 2002. Since then, other Web development tools, such as Wordpress and Typo, have also added trackback support. This allows bloggers from all types of platforms to communicate with each other. For example, a user might read a blog entry on another person's site and decide to post his own blog, responding to the original post. If he adds a trackback link, the original blogger will see that the other user has linked to his blog. Depending on the trackback settings, the new blog may also show up as a link at the end of the original blog.

Since trackback requires multiple websites to support the trackback protocol, it continues to be used primarily for blogs. However, some news websites now offer trackback links as well. You can tell if a site supports trackback if there is a "Trackback link" or "Trackback URL" at the end of an article. Sometimes the link will be followed by a number, which indicates the number trackbacks that link back to the blog.

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 <table> tag is used. The data that should be inside the table follows the <table> tag, and the table is closed with a </table> 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 <b>best website</b> 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:

<font="Times">This is the Times font, and <i>this is in italics</i>. Pretty exciting, huh?</font>

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. If you want to build a Web site of your own, you can either create it from scratch (using a text editor and typing your own tags) or you can use a layout program like Macromedia Dreamweaver, which will generate the tags for you. Best of all, tags used in markup languages don't itch or chafe your neck.

T1

This is a data transfer system that transfers digital signals at 1.544 megabits per second (quite a bit faster than a 56K modem, which maxes out at around 0.056 Mbps). Most small to mid-sized colleges and business have T1 lines for their Internet connections. Because of the T1's large bandwidth, hundreds of people can be accessing the Internet from one T1 line. However, like all good things, too many people on one T1 line can cause dramatic decreases in data transfer speeds. For this reason, multiple T1s are often used.

Telnet

This is a program that allows you log in to a Unix computer via a text-based interface. If you have an account on a Telnet server, you can access certain resources on the system such your home directory, your e-mail account, FTP files, etc. The downside of Telnet is that, to use it, you need to use Unix commands, which can be a challenge.
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