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This page contains explanations of technical terms used on this site. Links on this page may take you to other pages on this site or to external websites.

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A Microsoft technology, properly referred to as an ActiveX control, used to run small programs on the users computer. ActiveX controls are often used in standard application software but can also be downloaded and run. See also Flash™ and Java™ applet.


Used to refer to the traditional telephone line as opposed to digital. For computer communication to work the use of a modem is required to convert the computer's digital information into analogue. See also ISDN



Software used on computers to enable them to, for example, view content on the web. Browsers are also being used as an interface for kiosks and for computer applications. Two of the best known internet browser products are Firefox™ from the Mozilla Corporation and Internet Explorer™ from Microsoft.


With reference to websites it is the holding of information in memory as well as hard disc. Data can be retrieved from memory much faster than from a hard disc therefore performance is increased.

An access method to data services. Traditionally used for provision of television services typically in urban areas as an alternative to terestrial and satellite broadcasting. The existing infrastructure was extended to provide data services particularly internet access. In the provision of internet access competes with DSL.

Small files stored by your browser either temporarily or permanently. They are used, for example, to identify the user so that previously stated preferences are presented on your return to a website. Cookies are also used for internet shopping and more controversially by advertisers to track user browsing habits.

Short for Content Management System. See this page for more details.

Cascading Style Sheet. A webpage can contain content and styling. The styling can determine such things as: font size, font colour, typeface, text enhancement (such as underline, bold, italic), page background colour, etc. Traditionally content and styling were combined together. CSS was introduced, by the W3C, to separate the styling from the content. The stylesheet can be part of the same document, but in a separate section, or in a different document. The CSS approach has many advantages including easier to read code, styling can be changed globally and provision of different styling for different user agents. More than one stylesheet can be applied to a document at the same time where pre-defined rules determine how the inheritance cascades from one stylesheet to the next. Although stylesheets can be used for other document types webpages are probably the most common application.

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dial-up account
Prior to the rise in popularity of broadband services provided through DSL and Cable this was the most common means of access to the internet for housholds and small businesses. The user's computer is connected to a telephone line via a device called a modem which in turn is connected to another modem and computer at the internet service provider. The user has an account with the internet service provider which will probably have a name and password requirement to allow access. Additional services provided often include email and webspace.

see search engine

The virtual location for a website (or other content/service), often written in the form of an URL Computers use numbers to communicate with each other but humans are generally better at remembering names. When humans use the address computers will translate this into numbers and use this to connect one computer with another. Domains are also used for many other services, for example, email. Most people will be familiar with email addresses taking the form where the part after the @ is the domain part.

An acronym standing for Digital Subscriber Line. A technology used to deliver data transmission over telephone lines. Lower frequencies are used for traditional telephone services and higher frequencies for the data. The one physical line can then be used for both a telephone and data access at the same time.

The most common form of DSL, in most countries, is ADSL where the A stands for Asymmetric. An asymmetric line has greater transmission speed in one direction typically faster download speed than upload. This fits the pattern of most users of data rather than data servers. As the technology progresses new versions are appearing, for example, ADSL2+.

The other common form of DSL, but much less common than ADSL, is SDSL where the S stands for Symmetric. An SDSL line will have the same speed for both upload and download. As the provision of a symmetrical service is more costly it is more usually provided to businesses.

When used with reference to websites dynamic means the content of the webpage changes frequently. Typically the content will be stored in a database and when a user requests a page the content is created using the latest information. Examples include news sites, ecommerce, wikis and blogs. Compare with static.


E-commerce or ecommerce are shorthand for electronic commerce. Most often used to refer to purchases made over the internet using a credit card for payment. Payment can also be made using other means such as bank transfers, cheques and debit cards. Purchases can be both goods and services. M-commerce is a similar technique for purchasing remotely from the supplier this time using a Mobile (telephone or similar device).

Shortened version of electronic mail. Most email is now sent via the internet though some is also sent to recipients via internal company networks. Many organisations with email have interfaces from their internal systems to the internet. Email can be sent from computers, mobile devices and via some television sets. Popular email client software include Mozilla Thunderbird™ and Outlook Express™ from Microsoft.

The predominant technology used to network together computers to create a local area network. Ethernet uses cables to connect the computers and other devices together as opposed to Wireless networking which uses radio waves.


Icon or small graphic which is displayed in your browser when you visit a website. Mozilla's Firefox™ displays the favicon in the browser address bar, current tab and in the bookmarks.

A technology introduced by Macromedia Inc who are now owned by Adobe. Flash is most often encountered on the web as a means of displaying moving images (animation) and video. However, the use of Flash is wider than that as it is possible to have whole applications coded in Flash, for example, online gambling sites often use it. Although the technology is proprietory free player plugins are available for most browsers. See also Java™ applet.


A recursive acronym standing for GNU's Not Unix. GNU is an organisation which has developed and promotes free software particularly for Unix™ like computer operating systems. GNU is used alongside the Linux™ kernel to provide a complete free operating system. The easiest way to get this operating system is to use a distribution such as Debian GNU/Linux. Free is often defined as in "free speech" because the source code is freely available. GNU software is also often free of charge but this is not a requirement as organisations can charge for technical support, documentation, consultancy etc.

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A term used to describe allocation of space on a computer, attached to the internet, which holds a website. When a browser makes a request for a webpage it will be directed to a webserver hosting the website.



The huge international network of computers which are linked together and make possible services such as email , the web, instant messaging, file transfer and others. The population of connected computers swells enormously by the addition of personal computers (and other devices such as mobile 'phones) connected temporarily by dial-up, cable and DSL.

Stands for Integrated Services Digital Network. Uses a digital standard rather than analogue for communication by telephones, faxes and of course computers. Since the introduction of ADSL the use of ISDN for computer data transmission has all but disapperead in the UK. Some countries, for example Germany, use ISDN as the basis of their ADSL service.


Java™ applet
A proprietary technology created by Sun Microsystems using the Java™ programming language. The word applet is used to describe something smaller than a large scale application such as an email client or word processor. Java applets are generally encoutered when browsing websites where they are used to deliver content or perform services. The Java™ applet will require the user to have a Java Runtime Environment installed which is available free for many computer platforms. In some ways Java™ applets and Flash™ can be seen as competitors.

A computer scripting language most commonly used to add functionality to a webpage. When used on a webpage the code will run on the users computer rather than the webserver. Browsers supporting JavaScript usually have the facility to disable its use.


A computer, display and at least one input device (e.g. touchscreen or keyboard) in a self contained unit which provides a particular service. See this page for more details.

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The web is made up of millions of individual pages which can be accessed using URLs. Typically a user will read a web page using a browser and be able to access other pages using links on that page. The user could navigate by typing the URL into the browser's address bar but it is much more convenient to click-on a link. Links are commonly denoted by a different colour or a ext enhancement such as underlining. For example, this is a link to the Crann Tara home page. Links are also frequently associated with images. The images used for links often convey they are a link by looking like a button or similar. Image links are however problematical for users who do not use graphical browsers, for example, people with sight problems. For this reason it is important that image links have alternative text descriptions (alt tags).

The kernel created by Linus Torvalds which is used in combination with GNU to provide the free operating system GNU/Linux.

local area network
Often abbreviated to the acronym LAN. Refers to the connection of several computers, and other devices such as printers, into one logical grouping. Computers, and particularly notebook computers, can join the LAN using wireless networking as long as there is some kind of access point.


A shortened version of modulator-demodulator. A hardware, and sometimes partly software, device used to connect a computer to an analogue telephone line. Converts computer digital information into analogue so it can be transmitted down a telephone line and converted back again at the other end. DSL and Cable use similar technology, as well as Mobile telephones (datacards) and satellite services, where the devices are also called modems. DSL and Cable modems are much more complex devices which typically also offer other services, such as, routers and wireless networking.



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Most often used to refer to an additional piece of software added to your browser to enable some extra functionality. Popular plug-ins include Adobe Acrobat™ which provides a document format (PDF) and Java™ Applets from Sun Microsystems.

An acronym standing for Pan, Tilt, Zoom. The phrase PTZ describes the capabilities of a robotic webcam. Pan is the movement left and right, Tilt is up and down and Zoom is the ability to change the focal length of the lens.



With reference to websites, redundancy, is the provision of two or more identical resources rather than one. Should one resource become unavailable or too busy there are others that can be used. This has implications both for availability and performance.

Depending on the version RSS is an acronym for Rich Site Summary, RDF Site Summary or Really Simple Syndication. Regardless of version the intent is to provide a means for website users to be notified of changes to content on a website. A special type of file, XML, is used by the site owner that describes the content on the website and (optionally, but usual) the dates when they were last changed. Users read this file using a special software program called a Feed reader or Aggregator. RSS is most commonly used where website content changes fast and it would be impratical for users to check if anything had changed manually. Each version of RSS uses a different format of XML file describing the data. Feed readers are usually able to read all the formats. Atom is another syndication standard.



search engine
A very large database which can be accessed and interrogated to find information on the Internet. The owners of search engine use software tools, called robots, to go out and search the Internet for information, including websites, which are stored in databases. Popular examples are Google and Yahoo. A related area are directories which list information under predefined sections, a popular example is The Open Directory Project. Many search engines also provide directory services and vice-versa.

shopping basket
Used in e-commerce websites to enable multiple purchases at once. The analogy is that with a basket you can place many items into an then proceed to the checkout and pay a single amount. In North American English the term shopping cart is probably more commonly used.

See website

site traffic
A term which describes the number of visitors to a particular website or web page. Statistics for very popular websites often refer to 'hits' or 'clicks' per day or hour. Every time a webpage is requested it is considered to be a hit. The accumulation of these hits are considered to be the site traffic. Techniques are available to determine where these hits come from (e.g. the same user returning to a page) and these are excluded from the site traffic so as to determine unique visitors.

Secure Socket Layer. Most people will encounter SSL when they are making purchases via ecommerce websites. In such situations it is important that you can trust that you are communicating with the correct organisation and that your transaction is kept secret. The SSL certificate should match the domain you are buying from and is then used to encrypt the communication between your browser and the web server. The SSL certificate will have been issued, or authorised, by an authority which is considered trusted.

When used in conjunction with websites static means the content is relatively unchanging. The content may have been created using a text or web editor, saved to a location on a computer and then the same content is then served to users time and again by the web server. Compare to Dynamic content.


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Is an acronym standing for Uniform Resource Locator. URLs are alphanumeric strings that are used to describe the location of a resource on a network (including the internet) or on your own computer. Familiar to many people are the URLs that are used to describe the location of a document on the web, for example,

user agent
A user agent, defined here for internet purposes, is the, typically, software application used to access content or communicate via the internet (or other network). An internet browser, such as Mozilla Firefox™, would be one of the more common user agents. There are many other types of internet browser such as text only browsers, for example Lynx, or screen readers typically used by people with sight deficiences. Browsers are not the only type of user agent. Applications used to read email, communicate with other users, send/receive files or collect data can all be considered as user agents.



World Wide Web Consortium (W*3+C). W3C is the international standards body for the Web and related technologies.

Web Accessibility Initiative - an initiative to improve access to the web for people, typically, with physical disabilities. The WAI defines guidelines for Web Content, User Agent design (for example web browsers) and Authoring Tool design (tools to create content). For more information go to the W3C website.

The part of the Internet which is accessed using a browser. Information can be presented in the format of text, images and sound. The analogy is that of a spider's web because you can find many ways of getting from one place to another.

web accessibility
See WAI.

A computerised camera which is used to provide static or video images to a single computer, local area network or the internet. See this page for more information.

A definable part of the web allocated to one person, company or other organisation. Each site typically has one or more pages with a set of links which enable navigating around the site or between sites. See also domain.

website hosting
See hosting

A service offered to enable people and companies to have websites which require hard disc space. Services offered often refer to the amount of space, for example 20Mb.

wireless networking
Often abbreviated to WiFi, WLAN or 802.11. Refers to the connection of computers to a local area network by means of radio transmitters and receivers. Typically used by mobile type devices, such as laptop computers, and where the provision of cabling is unfeasable or unwanted. A device called an access point is required to send and receive the radio transmissions between the local area network and the wireless devices.

An acronym standing for What You See Is What You Get. Typically used to describe word processing or content producing interfaces which allow the user to see the presentation style and layout as the content is being produced.


Extensible Markup Language. A language which is used to store or convey structured data in a standard way. It is extensible because you are allowed to define your own elements. XML is the basis of, for example, RSS and XHTML.

Extensible Hypertext Markup Language. Traditionally, and still very common today, webpages were written using Hypertext Markup Language (HTML). However, the W3C considered that HTML did not provide a good basis for an ever expanding World Wide Web and introduced a new standard XHTML a variant of XML. XHTML is more flexible than HTML but is also more strict in its rules. There are several variants of XHTML.



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The above list is not intended to be exhaustive only covering the terms used on this website.