glossary of internet terms - d

A COMPLETE LIST OF DEFINITIONS OF THE TERMS USED THROUGHOUT OUR WEBSITE

Use the letters below to jump to a particular section or scroll down through the definitions.

misc A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Data rate - The speed at which digital information is transferred from one device to another, and can range from a few kilobits to many hundreds of megabytes per second. Traditional modems, for example, offer download data rates of up to 56Kbps.

Data table - In the context of a spreadsheet, a table of figures used to create a chart.

Database - Any collection of information, usually (but not always) used to refer to information stored on a computer. Database software applications usually include powerful search and data-filtering facilities.

Daughterboard - A small card containing support circuitry for a larger expansion card, plugged into a socket on the main card or connected via a cable.

DDR (Double Data Rate memory) - A type of memory that's twice as fast as ordinary memory. DDR memory is often used in graphics cards can now be found in PCs too.

Decoder - A home cinema component that converts the surround sound soundtrack on a DVD movie into a signal that's sent to an amplifier. Decoders and amplifiers are often combined into a single unit

Decryption - The process of making encrypted data readable again.

DECT -
Stands for Digitally Enhanced Cordless Telephone, a technology used by some cordless telephones to maintain clear call quality over long distances.

Default - A standard software or hardware setting. Most programs, including the Windows operating system itself, ask you to make a series of selections in order to perform a task. Sometimes the computer will already have made some selections ? these are called the defaults. You can change the defaults to fit your own preference, or accept them as they are supplied.

Defragment (or 'defrag') - To reorganise the data stored on a hard disk so that it can be accessed as quickly as possible by the computer. A fragmented disk can adversely affect system performance.

Degauss - To remove the magnetism from a device, usually a monitor. Most monitors degauss automatically but some have a button.

Desktop - What you see when you first start up a Windows-based computer. The Desktop will display your Taskbar and a selection of icons such as My Computer and Recycle Bin.

DHTML Dynamic HTML - This is an extended version of the language used to describe web pages, which allows a page to change instantly when certain things happen, for instance the mouse moving over a specified area.

Dialogue box -
A small window that pops up to display or request information. In Windows, Menu options that end with an '?' always open a dialogue box.

Dial-up Networking - A component of Windows that allows PCs to connect to the internet using a modem and a telephone line.

Diamondtron - Tube technology introduced by Mitsubishi in 1993. It uses the same principle as Trinitron aperture grille technology but with three electron guns at the back of the monitor rather than one.

Digital - Unlike the smooth signal of analogue, digital information consists of discrete parts. An analogy would be a car's gearbox. A vehicle can be in first or second gear, but not first-and-a-half. Computers only recognise digital information, so must convert analogue signals. A soundcard, for example, converts the sound of a recording into a series of numbers the PC can process.

Digital camera - A camera that stores images in computer memory rather than on light-sensitive film.

Digital signature - A piece of encrypted data that can be used to verify the identity of someone who sent the message to which it is attached.

Digital stabiliser - A method of removing small video camera shakes, such as the normal shaking of the operator's hand, by adjusting the picture by a compensating amount. Poorly implemented, it can cause a sudden jerk when you start an intended camera move.

Digital zoom - Optical zoom is the normal camera method of magnifying a scene by changing the distance between the different elements of the lens. Digital zoom allows even greater magnification by expanding each of the dots, but at some cost to quality.

Digitising - Changing an analogue signal, such as an audio/video recording, into digital data on a computer.

DIMM -
Dual Inline Memory Module. A slot-in card used to expand the memory of a desktop PC.

Directory -
An old name for what we now call folders. These provide a way of organising files and documents on disk, by grouping related items together.

DirectX -
Windows feature that ensures that all programs work with all the different types of hardware available.

Disk spanning -
Copying data from one disk to several smaller ones, automatically. This allows, for example, a large file to be copied from a hard disk to several floppy disks.

Dithering - Process of creating colour shades by adjusting the value of adjacent pixels to give the appearance of more colours than a device, usually a monitor or display panel, is actually capable of displaying.

DivX - A video compression standard that allows high quality video to be stored in small files. Freeview

DLP - A new technology used for projecting images from a monitor onto a large screen for presentations.

DLP projector - Produces a display by reflecting light off microscopic mirrors.

Docking cradle/station - A receptacle for a portable device, like a palmtop computer or a digital camera, and connected to a PC. Through this, the linked machines can exchange documents and data.

Dolby digital - A standard for high-quality digital audio used for video stored in digital format, especially on DVDs.

Dolby Pro Logic - A way of encoding audio information, developed by Dolby Labs.

Dolby Surround Sound - A system which literally surrounds the listener with sound, usually employing several speakers positioned around a room and controlled by a special decoder. Surround sound is used in feature films and many TV shows.

Domain name - The name used to identify a site on the internet, such as computeractive. co. uk or microsoft. com

DOS - Stands for Disk Operating System. The standard PC operating system before the dawn of Windows. DOS manages how files are stored on your PC. It is controlled through typed commands.

Dot matrix printer - Prints by hammering small 'needles' through a typewriter-style ribbon. This type of printer is noisy and only really used where continuous-sheet paper or multi-part forms are required.

Dot pitch - The distance between the dots which make up the image on a monitor.

Dots per inch (dpi) - The way the resolution of printed and scanned images is measured. Both types of picture are made up of dots. The more dots there are per inch, the smaller they are and the better the picture looks.

Double-click - To click twice quickly in succession on a mouse button. If you double-click on an application icon, Windows will then attempt to launch the application.

Download - Process of transferring files onto your PC directly from another computer. You might, for instance, download pictures and files from the internet.

Drag - In Windows, the action of clicking on something with the left mouse button, keeping the button pressed and moving (dragging) the object.

Drag and drop - A feature of operating systems, including Windows, which allows you to easily move and manipulate on-screen objects and files. For example, if you want to delete a file from the Windows Desktop, you move the pointer to the file's icon, click once to highlight it, then press and hold down the left-hand button. The item can now be dragged and dropped into the Recycle Bin.

Drag out - Click and hold down the left mouse button as you move the mouse.

Drive bay - A blanked-off space at the front of a desktop PC originally designed for additional floppy disk drives. Now drive bays accommodate all manner of peripherals.

Driver - Software needed to allow Windows (and other operating systems) to communicate with a peripheral. While Windows has many built-in drivers, often hardware-specific versions will be provided on CD-ROM with a new device.

Drop-down menu - A list of options displayed beneath a menu bar when you select a menu option, or when you click on a down-pointing arrow in a dialogue box.

Dropper tool - In image-editing, this is a feature used to set the foreground or background colour of the current drawing tool by simply clicking on part of an image.

DSL -
Electronics that apply special effects to digital audio to improve its sound or to make it sound like it's in a certain environment,such as a concert hall.

DSP -
Digital Signal Processor. Electronics that apply special effects to digital audio to improve its overall sound or to make it sound like it's in a certain environment, such as a church or concert hall.

DSTN - A type of flat-panel display used primarily on budget notebook PCs. They are of lower quality than TFT screens.

DTP (desktop publishing) - The design, layout and printing of documents, books and magazines using special software, such as Microsoft Publisher.

DTS - Digital Theatre Systems. A digital movie soundtrack format used in cinemas and on some DVD movies.

DTS Neo:6 - A digital movie soundtrack format used in cinemas and on some DVD movies.

Dual band - A mobile phone that can work at two radio frequencies. Vodafone and Cellnet use the 900MHz band, as do most networks around the world. Orange and One2One use 1,800MHz. Only a few other countries use 1,800MHz. Dual-band phones can use either frequency, increasing the number of countries they can be used in.

Dual-layer DVD - A DVD that holds twice as much data as an ordinary DVD by adding an extra layer.

DV - Digital video. A DV camera stores images on digital medium.

DVC - Digital Video Cassette, the latest video standard used in digital camcorders only.

DVD - A type of disc able to store huge amounts of digital data, including full-length movies, with excellent-quality sound and pictures.

DVD RW - A rewritable version of the DVD-R format whose discs are compatible with most DVD players and DVD-ROM drives

DVD+R - One of the emerging recordable DVD standards. It uses DVD+RW disks that are designed to have data recorded on to them time and time again. Movies recorded on to DVD+RW disks are fully compatible with DVD players

DVD+RW - A rewritable version of the DVD+R format.

DVD-R - Standard for Digital Versatile Disc-Recordable format, or blank DVDs onto which information (such as data or music) can be recorded ? but only once. Playable on most DVD players and DVD-ROM drives. You need a DVD-R drive to record onto DVD-R discs.

DVD-RAM - One of a number of competing standards for recordable DVD.DVD-RAM is really only of use in DVDRAM drives fitted in computers and some set-top DVD recorders.

DVD-ROM drive - These drives will play both CD-ROM and DVD discs. Huge amounts of data can be stored on one DVD disc, which looks just like a CD, including full-length movies, with excellent-quality sound and pictures.

DVD-RW - A rewritable version of the DVD-R format.

DVI (Digital Video Interface) - A video connection used on some TFT monitors and graphics cards that provides a purely digital connection between a PC and monitor. This gives a higher quality image than using a standard VGA connection.
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