Science, Maths & Technology


Updated Thursday 8th December 2011

An A to Z of IT and Internet terminology

A computer keyboard Copyrighted image Icon Copyright: BBC
Asynchronous Digital Subscriber Line
This high speed telephone connection enables fast downloads from the Internet. With an ADSL connection the computer is connected to the Internet permanently. The data flow is not the same when uploading and downloading, but it is on average between 10 to 40 times faster than a modem connection. A useful Web site for information is
Applets are small applications, often embedded within a web page. They are writtenin the platform independent programming language Java.
Active Server Pages
ASP is a Microsoft technology that is used to create dynamic web pages. Pages using ASP are created using VBScript, Perlscript or Javascript and are incorporated into the HTML of a web page. It is often used for database access or for other interactive functions, and requires the server to run Microsoft Internet Information Server (ISS) software.
Bandwidth is the maximum amount of data that can be carried by your Internet connection. If you have a low bandwidth, Web pages and graphics will take a long time to download. If you have a modem connection, your bandwidth is limited by the copper wire that carries the signal.
A bitmap is a type of graphic made of individual dots called pixels (picture elements).
Broadband is a type of data transmission medium (i.e. a wire or a cable) that can carry several channels at once. Most communications between computers, including Local Area Networks use broadband connections.
A browser is a software program that interprets and arranges all of the multimedia elements contained within a Web page. Two of the most popular browsers are Microsoft's Internet Explorer and Mozilla Firefox.
Common Gateway Interface
CGI is a standard for interfacing external applications with Web servers. An example is a CGI program that allows you to hook up a database with the WWW, to allow other people's browsers to access it. CGI allows the Web to input data into the database, and then display the information once it is retrieved.
Chats are a way for people to communicate in real time over the Internet. They are text based and nowadays are often applets written in Java and embedded in a Web page. One of the original chat applications was IRC, or Internet Relay Chat.
A cookie is a message delivered to your Web browser which is stored on your computer and can be read each time the browser requests a page from the server. The main purpose of a cookie is to identify users. This information can be used in a number of ways, one of which is to customise Web pages for return visits to Web sites. There are many uses for cookies, some benevolent, some malevolent.
The plural of the term datum, a single piece of information. Software is divided into two general categories, software and data. Programs are collections of instructions for manipulating data. On a computer, data is stored as bytes, units of storage capable of holding a single character.
A database is a way of storing information in categories. A computer database is a software package that is able to store lists of repetitive data, linked by keys, or common characteristics.
Domain Name
Every computer on the Internet has a discrete numerical address, known as an IP address. (E.g. To make it easier, these are given names, such as .
E-commerce is simply buying things over the Internet. See our FAQ for more details.
Encryption uses mathematical formula to scramble data for security purposes. The encrypted data is then stored in keys. These keys are kept by both the sending and receiving parties. The data can be decoded using the key. The data cannot be unscrambled without the correct key. Encryption is used in e-commerce (see above).
Frequently Asked Questions
FAQs are a list of questions often asked by people about a subject.
A file is a collection of information that a computer uses. It is always stored in a particular format. For example, a Web page is a file that is saved in html format. This format allows applications such as browsers to open them and read them. A file usually has a filename, followed by a full stop, and then a three or four letter file extension. (E.g. index.htm)
Geek is a common term for someone who is obsessed by their computer, and has achieved a high level of expertise in their chosen area. You could safely assume that most of the OpenLearn team are geeks.
A grayscale image is one that only uses shades of gray to describe its content. A grayscale image contains no colour information at all.
The number of times a Web page sitting on a server has been accessed. A server answers this number of individual requests in order to render a Web page completely. If a Web page contains a number of elements, each element is counted as an individual hit. The more hits, the more successful your Web page!
Hypertext Mark-up Language
HTML is the scripting language that is used to create Web pages. It is a high level computing language that is interpreted in a browser. It consists of tags that are used to describe the formatting in the page. HTML can also incorporate multimedia elements such as graphics, digital video, sound and animations.
Hypertext Transfer Protocol
HTTP is the protocol used for browsing Web pages on the Internet. Typing http:// into a browser tells the software that this is the protocol that you are going to use.
Strictly speaking, the correct term is glyph. An icon is a visual representation of a concept or idea. In computing it takes the form of a small graphic, which when clicked, launches an application.
Image Map
An image map is a way to code HTML so that a single image can contain a number of clickable elements. Hotspots on image maps are defined by exact pixel co-ordinates. These hotspots can take you to another Web page, or to somewhere within the existing page.
A programming language developed by Sun Microsystems. It is a platform independent system, using what is called a "virtual machine", a separate programme that allows an application to be executed regardless of the sort of computer it is accessed from. It is an object-oriented language similar to C. Java applets are often embedded in Web pages.
Joint Photographics Experts Group
A jpeg/jpg is one of the standard image formats used on the Internet. It uses "lossy" compression which often leaves artefacts in the image. Its advantage is that jpeg files are often very small and can be transferred quickly over modems.
Short for Kilo or Kilobyte Most people think that kilo means 1000. But in binary systems, a kilo is 1024, (2 to the 10th power). A kilobyte is therefore 1024 bytes of information. In computers a kilobyte is often shortened to K or Kb.
A public terminal that allows access to anything from a database to the Internet. Electronic kiosks have to be user friendly and robust, with simple interfaces. They usually use touch screens.
Local Area Network
Most work places have their computers on a network, also known as a LAN. LANs allow users to move files around the networks of computers connected to the LAN. Some LANs are connected to the Internet, but without the protection of a firewall, there can be security risks.
A layer element allows a HTML author to position content in a Web page. It uses absolute pixel positioning for this content, and there is liable to move depending on different computer screen resolutions on the user's computer.
A login name is a series of letters or numbers that have to be inputted before you can log in to a computer, or an email account, or internet connection. A login provides basic security for users.
Meta Tags
Meta information is stored in the head of an HTML document. This information provides details such as keywords and descriptions to a Web page.
A mouse is an input device that enables human-computer interaction.
Moving Pictures Experts Group
A group of audio/video compression standards that are used to make videos for the Internet. To view the audio or video, a player is needed. Most computers these days come with players that are able to play files of this type.
MPEG layer 3.
This is an audio file compression method that converts recorded sound into a highly compressed digital format. MP3's can be replayed on a computer, or downloaded into portable MP3 player
The Net
An abbreviation of the Internet.
Code of behaviour on the Internet.
A number of computers linked together in order to share resources, swap files, or access databases.
A NetCast is a broadcast over the Internet. It is usually broadcast live. was the website which supported BBC and Open University programming between 1999 & 2011. Its content now lives on OpenLearn.
Open Source Software
Open source software is software for which the underlying code has been made available for users. Users are then able to read it or change it as they wish. Linux is an example of open source software
Packet Switching
Packet switching is the method used to send data around the Internet. It works by breaking data into chunks, each chunk has an address of where it came from and where it's going. These chunks are then sent by various routes across the Internet to the destination machine, which re-assembles them in order.
See login
A piece of software that adds extra functionality to a larger application programme. The Flash player, Quicktime player and Real player are all plug-ins for Internet browsers.
A small window that "pops up" on your screen. Pop-ups are usually programmed in javascript and are often created to be smaller than the normal browser window.
An audio/video technology developed by Apple. It can be played both on the PC and Apple Macintosh machines. It is available as a plug-in, but is incorporated in more recent browser software.
Resolution is the sharpness or clarity of an image. It is often used to describe monitors, printers and bitmapped images. A screen resolution refers to the number of dots (or pixels) on the entire screen. An 800x600 screen resolution displays about 480 000 dots on a screen. The more dots, the sharper the image.
A dedicated computer that sends packets from one place to another on the Internet.
Search Engine
Search engines are invaluable for finding things on the Internet. They use keywords to identify Web pages that contain similar information. Google, Lycos, Alta Vista and Hotbot are all excellent search engines.
A Web server is where a Web page and other data "resides" on the Internet. It is called a server because it "serves" or delivers Web pages when requested. It uses the HTTP protocol for Web pages, but other protocols may be used, such as FTP.
Service Provider
In order to access the Internet, you need to have a service provider. These are companies that provide a dial-up or broadband service so that you can connect to the Internet.
A <table> is a tag in HTML that creates boxes on the screen. It contains table row <tr> and table data <td> attributes. Tables were previously very useful for page layout, but the use of newer methods like CSS (cascading style sheets) are now preferred.
A tag is part of the HTML (Hypertext Mark-up Language) scripting language that is used for web pages. A tag is a command that specifies how a browser will render and format a Web page. In HTML a tag is enclosed in greater and lesser than symbols . For example, an italicised word will be encapsulated by two <i>text</i> tags.
Otherwise known as a font, a typeface is the design of a set of characters. Times Roman is the name of a typeface, as is Arial. Times Roman is an example of a serif font (it has extra lines, or serifs at the bottom of each letter) , and Arial is a sans-serif font.
Underline is a tag in HTML. You make an underline like this:<u>text</u> In a browser, it looks like this: text
Unix, along with Linux and Windows is one of the most commonly used and oldest operating systems. Unix is very robust and can be run on just about any hardware platform available. Many Web servers use Unix, but it has a broad range of other uses, such as banking, video games etc.
User Interface
A computer science term, an interface is the point of communication between a computer and an external entity, (in this case, a user). It is a term often used when someone wishes to describe how a Web page is designed in terms of usability. A "good" user interface will be intuitive and easy to use. A "bad" user interface is confusing and difficult.
Validation is a way to make sure that your code is compliant with the W3C HTML specifications. Validation sites include Bobby and the W3C's Validation Service.
When you download a Web page, you a "visiting" a Web site. Web authors can register your visit by using cookies.
World Wide Web Consortium
Founded in 1994 by Tim Berners-Lee, this consortium's aim is to establish agreed standards for the Web so that it develops in a unified manner. It determines the specifications for many of the authoring languages used on the www.
BBC WebWise is an online course run by the BBC to teach all things Internet.
World Wide Web
The World Wide Web was invented by Tim Berners-Lee in 1989 and is a hypertext driven system of pages made up of multimedia elements linked via the Internet.
Extensible Mark-up Language XML is used for Web pages as well as HTML (Hypertext Mark-up Language). It allows the author to customise basic HTML by creating bespoke tags and behaviours.
Originally a search engine, Yahoo has become a site that is a useful portal for anything from online auctions to virtual communities.
To "Zip" something means that you are compressing it, making it smaller so that it takes up less hard drive space. If you zip a file it will take less time to send over the Internet. Software programmes that zip files include Stuffit, Winzip for PC, Zipit for Macintosh and gzip for Unix machines. Don't confuse zipping a file with storing it on an Iomega Zip disk, which was a popular external backup storage device in the 1990s and 2000s; like a floppy disk, only bigger.

For further information, take a look at our frequently asked questions which may give you the support you need.

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