Glossary

See alternate text.

Such a text is important for visitors who cannot see the images, such as blind people and search spiders.

Series of images in a single GIF file, which create an animation when played in succession. SeeGIF.

The most frequently used server software, which is distributed free of charge. Apache runs on the Unix operating system, but is also available for Windows and Mac OS X. Apache is Open Source software.

Abbreviation for American Standard Code for Information Interchange. A character set of 128 characters in 7-bit encoding. Almost all computers can read files written in this character set.

Abbreviation for Active Server Pages. Microsoft programming language for dynamic generation of HTML pages. Like PHP, ASP can be written between the HTML code in document. When requesting a page, this code is executed on the server, after which the result is sent to the web browser. ASP is not an open standard.

Building block of a markup language. An attribute is applied to the opening tag of an element and contains complementary information for the element. In the HTML markup language, certain attributes are mandatory for certain elements.

If a visitor to a website wants to save the website address for a future visit, the visitor can make a bookmark for this website in his web browser. Bookmarks are called Favorites in Microsoft browsers.

See web browser.

Extra, quickly accessible memory, for storing frequently used information, so that it is made available more quickly. Web browsers have a cache memory in which they store web documents (pages, images, etc.).

Client-side technology for the specification of rules for the design of websites. Often abbreviated as CSS. CSS is supported by modern web browsers, but can be disabled or overwritten by users.

See character encoding.

See CSS Image Replacement.

On the side of the client: the web browser, search spider or other program that requests the document. Client-side internet technology is inherently unpredictable for web developers, because users of web browsers can disable this technology in the program or because it is not supported. Producing websites that depend on client-side technology is generally considered bad practice.

Examples of client-side internet technologies are ECMAScript, JavaScript, JScript, VBScript, Java Applets, ActiveX, CSS and Cookies. In a broader context, images can also be regarded as optional technology.

The counterpart of client-side is server-side, technology on the side of the web server, which the web developer does have overview and control over.

Client-side script is the term for program routines executed on the side of the client: the visitor's web browser. Examples of client-side script languages are ECMAScript, Netscape Communications’s JavaScript, Microsoft’s JScript and VBScript. See also client-side.

The information offered – the content – on a website.

The person who manages the content of a website.

A system for managing the content of a website. Often abbreviated as CMS. There are literally hundreds of systems available from at least as many providers. Many systems are web-based, which means that they can be accessed from anywhere by means of a web browser.

Technology that enables a web server to store a limited amount of information on a visitor's computer. This information – a cookie – is read by the server during each subsequent request from the web server by the browser. Cookies are used to identify the visitor to a site. They can contain information such as the date and time of the visit, user names or settings selected by the visitor for the website in question. Modern web browsers give the user the opportunity to disable some or all cookies, e.g. in the interest of privacy.

See Content Management System.

See Cascading Style Sheets.

Popular technique among web developers for designing websites with Cascading Style Sheets. This technique consists of hiding plain text in a HTML document and replacing it with a background image by means of CSS. Several different variations of this technique have been developed, such as Fahrner Image Replacement (FIR).

See database.

Electronic collection of data, aimed at retrieving information quickly and flexibly. Databases are available in different types and sizes, based on various structures for specific applications.

Examples of Open Source database software for application on websites are SQL, MySQL and PostgreSQL. Oracle and Microsoft Access are examples of database software that are not Open Source.

Dublin Core Metadata Initiative. See meta-information.

Each HTML document must begin with a Document Type Declaration (referred to as DocType); this declaration tells web browsers and markup validators which version of HTML or XHTML is being used and creates a link to a Document Type Definition (DTD) which specifies the grammar for the markup language.

The W3C Document Object Model (DOM) is a standard for describing the hierarchy of XML and HTML elements in the memory of the web browser. It is comparable to a tree model. DOM enables client-side scripting languages, such as ECMAScript to manipulate these elements and their design.

See DocType.

See DocType.

Document Type Description. See DocType.

See Document Object Model.

See meta-information.

ECMA stands for European Computer Manufacturers Association and is an organisation of companies that is dedicated to the standardisation of information and communication technology, in cooperation with organisations such as the ISO (International Organization for Standardization) and the ETSI (European Telecommunications Standards Institute).

ECMAScript is a standard for a client-side script language, combined from elements of Netscape Communications’s JavaScript and Microsoft’s Jscript. Much of ECMAScript centres on manipulation of the Document Object Model.

Building block of a markup language. An element consists of tags – an opening and closing tag – which surround the content to which the element has been applied. For example <em>Please note!</em>. In the HTML markup language, some elements only have an opening tag. For a few other elements the use of the closing tag is optional.

The opening tag of an element can contain attributes.

See Bookmarks.

Fahrner Image Replacement. See CSS Image Replacement.

A client-side technology for animations and interactive effects, developed by Macromedia.

A technique for presenting multiple pages in a single browser window. Sections in which individual pages can be loaded are reserved in a special page – called the frameset – within the window.

File Transfer Protocol, a series of rules, comparable to HTTP, directed at transferring digital files.

Abbreviation for Graphics Interchange Format, a file type especially for images, developed by Compuserve. The GIF file format uses a compression method that drastically reduces the image file size without affecting the quality of the image (lossless compression). The GIF file format is particularly suitable for stylised images and images without photographic detail.

A graphical control panel or screen that enables the user to use the underlying technology. This can take the form of e.g. windows, buttons and tabs. Operating systems like Windows and Mac OS X are examples of Graphical User Interfaces. Usually abbreviated as GUI.

See Graphical User Interface.

Abbreviation for Hyper Text Markup Language. Markup language used to structure web pages. HTML was developed as a platform-independent language, so that information can be read by any computer.

Abbreviation for Hyper Text Transfer Protocol. A set of rules for communication between servers and client-side programs (such as web browsers and e-mail applications) on the Internet.

A small piece of meta-information exchanged between the server and the client-side program when requesting a web document according to the HTTP protocol.

Hyperlinks are the threads of the Web; they make it possible for visitors to jump from one page to another by simply clicking a mouse button. Links come in all kinds of colours and forms, but the original format (in most browsers) is as an underlined text in a different colour.

See HTML.

Abbreviation for Internet Engineering Task Force. An international standardisation organisation which devises developing tools for the Internet. The IETF handles current (technical, economic and social) issues related to the use and operation of the Internet.

Image maps are images for which selections that link to other documents are indicated in the markup. The visitor can click on these selections in the image to follow the links.

Abbreviation for International Network. Worldwide network of hundreds of thousands of computers and computer networks connected to one another via telephone and/or data lines. In principle it is accessible to anyone. A characteristic feature is the decentralisation of the network: there is no central computer that drives the network.

Abbreviation for Joint Photographic Experts Group. File format for images. A characteristic of the JPEG file format is that compression reduces the image quality. The JPEG file format is very suitable for photographic images.

Character encoding is a term for a mechanism that takes place behind the screens of virtually every digital document and tells a computer which characters (letters, numbers, punctuation symbols, etc.) a document contains: bytes are translated into characters and vice versa.

In terms of web pages, the visual placement of page elements in the browser window.

Web developers often use tables to realise the layout of a website. CSS is better alternative.

See hyperlink.

The phenomenon of hyperlinks leading a visitor to a dead end, because they refer to Internet addresses that do not exist (anymore).

Web browser, originally for the Unix operating system. Lynx is an example of a text browser. Lynx only displays (unstyled) text and does not display images. Lynx is an ideal tool for web developers to check how search spiders and speech browsers interpret their websites.

See markup language.

Markup is a collective term for languages that serve to structure the content of text documents. Examples of markup languages are HTML and XML.

The basis of a markup language is formed by elements and attributes.

Programs for evaluating the markup of documents – such as the HTML in web pages. A markup validator can often check whether a web page satisfies the markup guidelines of the W3C. A number of validators, such as the W3C Markup Validation Service, are available online. There are also validators that are aimed at limited checking of accessibility aspects, such as Bobby or Cynthia Says.

See meta-information.

Meta-information (metadata) is information that says something about other information. For example, a web server uses an HTTP header to tell the web browser when a requested web page was last modified. Another example is the use of meta-information in the HTML source code of web pages for information on the author or a summary of the page. This information can be used by e.g. search engines. A popular standard for meta-information is the Dublin Core Metadata Initiative (DCMI).

Client-side method for automatically refreshing or redirecting a web page. The term is derived from a variant of the meta element that is placed in the HTML source code of a page: see metatag.

Jargon for the incidence of a meta element in the HTML source code of a web page. This element contains meta-information on the document.

Abbreviation for Multipurpose Internet Mail Extensions. The MIME-type of a file defines what type of file it is. Based on this, a web browser decides what to do during and after downloading the file. The user can instruct his browser what to do with files of a particular type.

See MIME.

The largest software manufacturer in the world. Microsoft was founded in 1975 by Bill Gates and Paul Allen. Founder Bill Gates sold his DOS operating system to IBM and kept the rights to it. As a result Microsoft was able to grow to become the number one software manufacturer. Microsoft's products include the popular Windows operating system and the Internet Explorer web browser.

Marc Andreessen is the co-founder of Netscape Communications. He founded the company together with his friend James Clark. The company's best-known product is its web browser. The name Netscape is a combination of internet and landscape.

Term for software whose source is open for implementation and modification and whose rights of use do not exclude any persons or groups. This does not necessarily mean that Open Source software is free of charge.

Open Source software guarantees open standards.

An open standard is a standard that meets the following requirements:

• The standards are defined on the basis of an open decision-making procedure (consensus or majority decision, etc.).
• The standard is maintained by a not-for-profit organisation that has a completely open admission policy.
• The standards are published.
• The costs of using the standard are low and do not create a barrier to accessing the standard. Any intellectual property that underlies an open standard is made available on a royalty-free basis.
• There are no restrictive conditions concerning reuse of a standard.

(Source: OSOSS)

See client-side.

Personal handheld computer. See PDA.

Abbreviation for Personal Digital Assistant; personal handheld computer. Also called a palmtop. PDA’s increasingly have the option of accessing the Internet via e-mail and a web browser. PDA manufacturers include Palm and Psion.

Abbreviation for Portable Document Format, a file format for text documents, developed by Adobe.

A somewhat obscure abbreviation for Hyper Text Preprocessor; a server-side programming language for dynamic generation of HTML pages. Like ASP, PHP can be written between the HTML code in a document. When requesting a page, this code is executed on the server, after which the result is sent to the web browser. PHP is an example of an Open Source product. PHP is an open standard.

Abbreviation for Portable Network Graphics. Technique used to reduce (compress) the size of graphic files. It is an alternative to GIF, but PNG (pronounced: ping) is free of rights and patents. PNG is better than GIF in many aspects: better compression, better greyscale support, more colours possible, etc.

See PDF.

Rules and agreements concerning the way in which something must be done. In terms of the Internet, everything two computers must comply with if they want to communicate with each other. For example, between a terminal and a computer or between a peripheral device and a computer.

See PNG.

See RSS.

See RSS.

Abbreviation for Rich Site Summary or Really Simple Syndication. RSS is an application of the XML markup language. RSS makes it possible to keep informed of updates on websites that provide an RSS feed – a concise summary of the latest content on the site. This information can be read by means of an application that can read these RSS feeds – an RSS reader.

Abbreviation for Rich Text Format. File format for text that contains formatting codes for text styles. Rich Text can be read by many word processing programs. Originally a Microsoft file format.

Special program used by people with a visual impairment. The screen reader reads the information on the computer screen and makes it accessible to programs that translate that information into speech or Braille.

A combination of computer assignments in a file. Examples of client-side script languages are ECMAScript and JavaScript. Server-side script languages include PHP and ASP.

On the side of the server, the web server. In contrast to client-side technologies, server-side technologies – such as PHP, ASP, SSI and Perl – are controlled and monitored by the web developer, and can therefore be applied more reliably than client-side technologies.

Sessions are a method of identifying visitors to websites during their visit. Sessions generally use cookies or, if cookies are not supported, a modified URL.

Unwanted, often commercially oriented e-mail. The official term is UCE (Unsolicited Commercial E-mail). Sometimes large quantities of e-mail are placed on newsgroups. The term is derived from tinned meat: Shoulder Pork and Ham. It was introduced by G.A. Hormel (1860-1946) and was mainly eaten by soldiers during World War II.

A program that ‘crawls’ the internet looking for new, publicly accessible resources, such as WWW documents and files in FTP archives. Also called wanderers, crawlers or ants. Spiders necessary due to the enormous growth in the supply of information. Popular search engines such as Google and Altavista have their own spiders to index web pages for their databases.

Abbreviation for Server Side Include. A simple server-side programming language that makes it possible to include HTML documents in other documents. This way a file can contain a menu that is included on every page by means of SSI.

A table is a collection of information divided into cells. These cells are distributed across rows and columns which clarify the relationship between the individual cells. On the Web, tables are used for the same purposes as in other media, the relational display of information. In addition tables are very popular for the realisation of the layout of websites.

Fragment of a markup element. Tags enclose text, which together forms an element. Examples of tags are <a>, </table> and <div>. Tags are also sometimes referred to as labels.

Miniature image (the size of a thumbnail or a postage stamp), which usually links to a larger version of the image.

Abbreviation for Uniform Resource Locator. Standard for addressing documents on the Internet. A URL – an Internet address – looks like this: http://www.yahoo.com/.

See markup validator.

Acronym for World Wide Web Consortium. Organisation founded in 1994 by Tim Berners-Lee. One of the objectives of the W3C is to achieve agreements concerning (future) standards on the Internet. The W3C is neutral. All major players in the area of the Internet are involved in it; this includes Netscape Communications, Microsoft, Sun Microsystems, IBM, Adobe Systems, Hewlett Packard and Novell.

Abbreviation for Web Accessibility Initiative, a working group of the W3C which issues guidelines for accessibility on the Web. Example of these guidelines are the WCAG (Web Content Accessibility Guidelines).

Abbreviation for Web Content Accessibility Guidelines, guidelines drawn up by the WAI (Web Accessibility Initiative) concerning accessibility to the Web. The WCAG concentrates on accessibility to web pages.

WCAG version 1.0 is characterised by the three priorities, each with their own set of guidelines which web developers and content managers can meet. A second version of this series of guidelines is currently under development.

The guidelines in the manual on this website are based on the guidelines from WCAG 1.0 priority 1 and priority 2. Accessibility initiatives such as the Quality mark Drempelvrij.nl use the guidelines from WCAG 1.0 priority 1.

Program used to view web pages. The browser converts HTML pages into readable text, and loads and displays images and multimedia files.

A number of graphic browsers (mostly free) are available, such as Netscape Navigator, Mozilla, Opera, Microsoft Internet Explorer and Safari. There are also browsers that only display text, such as Lynx, browsers especially for mobile telephones and PDAs and browsers that convert web pages into speech or Braille.

Person who builds or puts together a website, usually in terms of the technical aspects.

Computer that provides information. A web server is connected to the Internet and serves documents to clients, such as web browsers and spiders, on request. Multiple websites are often managed on a single web server.

See WWW.

See W3C.

Abbreviation for World Wide Web. Part of the Internet within which web pages are connected together by means of hyperlinks. The WWW can be accessed through a web browser. The WWW has been in use since 1991 and was invented by Tim-Berners Lee. At first, all the information was based on text, with images, sound and video added later on.

Abbreviation for Extensible Hyper Text Markup Language, a platform-independent markup language that is a reformulation of HTML according to the rules of XML.

Abbreviation for Extensible Markup Language. A platform-independent markup language for the specification of other markup languages. Examples of XML applications are XHTML and RSS.

Popular file format for combining and compressing files.

Term for a program or service that indexes information on a network or computer and searches through it on request, looking for specific terms entered by users of the search engine. Search engines that search through the unprecedented amount of information on the Internet – such as Google and Altavista – are extremely popular among Internet users.

Search engines on the Internet use search spiders to index web pages: programs that read through web pages, analyse and assess the content and enter it in a database. See also spiders.