Why Accessibility is important
Making web sites and pages accessible is an important part of designing for the web. There are large benefits to accessible design.
The more accessible that a site or page is, the greater the number of people who will be able to use the content it provides. An inaccessible site can restrict or remove access from a significant proportion of users. Durham University has a strong equal opportunities policy, and there is also legislation in place to prevent discrimination.
There are a wide range of different browsers and browser versions in use. Each translates (or ignores) HTML in a different way. Browsers exist for a wide range of display environments, from the obvious computer monitor, to text-only terminals, the small screen of a PDA or mobile phone, or non-visual media such as speech or braille.
An accessible page will be readable regardless of the user's choice of browser.
As well as human readers of your pages, there are many automatic systems that will search sites and pages regularly, usually for a search service. Accessible sites are more likely to rank highly in a search, as the search engine will be able to read more of the site into its database, and, if correctly written, categorise it properly.