Website Design Considerations
Accessibility
The whole point of a website is usually to be viewed by the maximum number of people with the minimum of fuss. There are many small features within webpages that can make all the difference to the browsing experience.
Despite all that has been said about browser support and modern standards there are still browsers out there that work very differently but are by no means obsolete.
The most obvious examples are text based browsers such as Lynx, WAP browsers with limited display facilities such as mobile phone devices, and text-to-voice browsers as used by the blind.
There are many ways to code webpages that will look fantastic and show off all manner of cool tricks, yet will bum completely in one of these 'special' browsers. In most cases this relates to the use of images containing text rather than pure text itself, few if any text-based browser are able to extract the required information and the resulting webpage will be a series of blanks. If these unreadable sections are also the links to other pages then the website will not only be unreadable but unnavigable too.
Never use images alone to display text or links to other pages, a similar argument applies to fancy Flash animations and other forms of embedded applications.
That's not to say that you cannot do this, after it can look good if it is done properly, but you must make use of the image 'alt' and the link 'title' attributes to ensure that even if the image cannot be shown there is an alternative piece of descriptive text that will make it clear what the image was and give it some context. In the case of links the title attribute is used to inform the reader where the link will take them.
All other forms of scripting and embedded applications should also be furnished with an alternative plain-text output for the same reasons.
Many accessibility considerations revolve around good design, it is important that your site can be navigated easily, by users as well as search engines. If search engines cannot locate your pages few people will ever see them! JavaScript is handy for building repetitive sections of pages, especially sets of navigation links, but these cannot be read by search engine spiders. Make sure that a plain HTML version of your links exists somewhere within your site for the search engines to index.