Markup languages format text, images etc. for digital devices. The standard language for web pages is Hypertext Markup Language (HTML), standardised by the World Wide Web Consortium (W3C). The latest version of HTML is Extensible Hypertext Markup Language (XHTML).

There is also Wireless Markup Language (WML) for small screens on mobile phones running Windows Application Protocol (WAP). The language Extensible Markup Language (XML) is not designed to format data on a screen, but describes the relationships between data items in a similar way to the fields and records in a database.

For a guide to CGI and server-side scripting, see General Topics - CGI and Server-Side Scripting.

Web pages are written using a text editor or a GUI program such as Dreamweaver (current standard is 8.0) which constructs the underlying markup code. Web pages should:

• Contain informative images.
• Display data effectively (e.g. in tables).
• Contain updated and valid links to other pages or sites (no dead ends, such as HTTP 404 - File not found errors, like this one)
• Access data from server-side databases.
• Make "reasonable accommodation" for visitors with visual, audio or cognitive impairment.

Document changes to a web site. This helps with security and assists later site designers to maintain the site.

When you log on to a web site you get the default page. This is usually called index.htm (so entering "www.mysite.com" actually accesses "www.mysite.com/index.htm") but varies from system to system (e.g. could be any combination of index, welcome, home or default with extensions htm, html, asp or jsp).

Site map - a page on the site giving an overview of its structure and allowing access to all sections from one place. May also include a search box to search the site.

Writing web pages with the disabled in mind

Visual impairment:

• Consider font-size for readability.
• Provide text-support (alternative text) for images and non-text items.
• Screen-reader support for audio rendition software.

Audio impairment:

• Ensure there is equivalent text for any audio presentation.
• If the site is supposed to have speech input, ensure there is alternative text input.

Also consider:

• Avoid strobing backgrounds or images for visitors with neurological problems.
• Navigation aids for those with cognitive problems.
• Possible low-resolution versions of screens.
• Consider those who are colour-blind (very common!)

The Americans with Disability Act (1990) applies to certain defined "covered entities" within the U.S.

• Stipulates the all non-text items (e.g. images and Java applets) have text-based descriptions.
• Specifies input forms should be created so that they can be read by screen-reading software.

The W3C developed the Web Accessibility Initiative to produce the Web Content Accessibility Guidelines (WCAG). Official software in the European Union mainly adopts this standard. Criteria for conformation are classed at three different levels, and different conformation standards (A, Double A and Triple A) adopt some or all of these.

Rehabilitation Act - Section 508. The main aim of this act is to allow disabled people the same level of access to sites as able-bodied people. It specifies 16 standards.

Child Online Protection Act (1998) intended to prevent children from encountering harmful material online. Infringement can lead to $50,000 and/or 6 months in prison!

Tools exist to validate web pages according to these various laws and guidelines. They can be web-based (as opposed to stand-alone), commercially available or freely available.

Audience Development Techniques

Push technology. Users request to be put on a client list to receive information (e.g. newsletter).

Pull technology. Information only sent to user when requested. Includes E-mail or files downloaded from sites.

Visitor tracking. Statistics about the number visitros to a site, which pages were visited etc.

Portals - jumping off points for huge numbers of web sites. Horizontal portals are general interest such as search engines and directories. Vertical portals serve one particular interest or subject.

A wiki site encourages visitors to contribute e.g. Wikipedia which is an encyclopedia with articles contributed and edited by visitors. Requires constant supervision to ensure high standards.

Databases - See file Internet Business Foundations, Chapter 4

Download time - the time taken to download a web page or file. Depends on network connection speed (from 14.4 kbps up to T1 lines at 1.544 Mbps) and file size. Remember, the download time for web pages depends on all the files it contains such as images.

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