Interoperability and Accessibility
A primary principle of accessible design is to create documents that do not rely on one type of hardware or software. Pages should be usable by people without mice, with small screens, low resolution screens, black and white screens, no screens or with only voice or text output, etc.
The Problem: Misusing the Language of the Web
Hypertext markup language (HTML) is the lingua franca of the web. It was originally designed to break down the barriers to communication between users of different types of computer systems and to allow anyone to publish information that is accessible by anyone else using a computer. Too often, however, web pages are created that work "best" with a particular browser, or that only work when using the most popular operating system and browser combinations. Sites like this are like a newspaper that is written entirely in slang or in a regional dialect for which there is no dictionary.
Merely checking that a particular page looks like it makes sense when viewed in Netscape Navigator or Microsoft Internet Explorer is not sufficient. Often, pages that are functional and meaningful for sighted users of these browsers are unusable and meaningless for other users. Not only are the most common browsers very 'forgiving' of errors that may cause pages to fail with other software, but they also recognize independent 'extensions' to HTML that are non-standard and unavailable to other users.
Furthermore, many web page authors misuse various HTML tags such as headings and tables to create a particular visual effect, neglecting to consider the result that this has for users who may be unable to see these effects and who rely on those tags to provide meaningful information.
The Solution: Use Standard Markup
The World Wide Web Consortium (W3C) publishes "Recommendations" that are like a dictionary for the HTML 'language'. They are the only non-proprietary standards for HTML and have an extremely broad level of international support. Using HTML or other markup, such as extensible hypertext markup language (XHTML) that conforms to formal published standards, such as the W3C Recommendations, is the best method to ensure that websites are accessible to the greatest possible range of users. The correct and meaningful use of valid markup is therefore a main theme in the WAI's Priority 2 Guidelines. (WCAG 1.0, Sections 3.3, 3.5, 3.6, 3.7, 5.1, 5.2, 5.3, 5.4)
Beyond making web pages accessible to users with disabilities, using HTML markup correctly has other benefits:
- Pages with valid HTML are more easily indexed by search engines. In fact, one of the most common recommendations made to ensure that a site is 'found' by search engines is that valid HTML be used. Often, search engines will actually reject pages with invalid code.
- Future users are more likely to be able to access HTML that meets standards which have been agreed upon by a broad international coalition rather than being optimized for one particular company's current browser. In fact, both Microsoft and Netscape, for example, have recognized the benefits of standardization and are committed to making future browsers which recognize the W3C's HTML 4.01 Specification, as well as the CSS 2.0 Recommendation for cascading style sheets.
Which Version of HTML Should You Use?
The latest versions of HTML and XHTML are defined so that they 'degrade gracefully' when viewed with older software. This means that with valid code there is no problem using pages that are written using the latest version of HTML with even the oldest text-only browsers, such as Lynx. At Jelve Design, we recommend using at least HTML 4.0 to ensure the widest possible audience and to make attractive content that can perform well into the future.
Another option is to use XHTML, which is a version of HTML defined so that it conforms to the stricter rules of extensible markup language (XML). XML is a new type of markup in which the information can be processed more effectively by computers and which has been designed to facilitate the exchange of information between the broadest possible ranges of computer systems. Using XHTML can have advantages for automating the publishing of new valid documents using a content management system, for example, and for making information available to a wider range of devices beyond the traditional personal computer and browser. Once a document has been constructed as valid XML, it may be transformed through an automated system to many other formats. It is possible, for example, to take a single XHTML document and to generate versions optimized for specific alternative devices such as WebTV or handheld browsers.
Which 'flavour' of HTML you choose depends on the nature of your documents, on your target audience and on the particular circumstances of your organization.