Accessible Design Guide

In the context of web site design, accessibility is a measure of how easy it is to access, read, and understand the content of a web site. Accessibility is complicated by the fact that a web site is not a published piece of work so much as a living document that can be interpreted in different ways by different browsers and on different platforms. Web sites are not a print medium- although they are most often read in a visual manner, there are many different ways a web page can be experienced, such as via a speech browser or via an indexing robot. A web page is a combination of textual information which is interpreted appropriately by a browser and linked to files of various types, such as graphics, movie clips and sound files.

Since a web page can be interpreted differently by different browsers with different capabilites, and since the language of a web page- HTML, is constantly evolving, accessibility must be considered to make a page usable by as many people as possible. The keys to making your page accessible are graceful degradation, standards compliance, fast loading, and intelligent organization.

Since HTML is continually changing and different browsers support different elements, graceful degradation is the key to making sure that pages are readable and accessible in all browsers. When a browser encounters tags it doesn't understand or can't display, degradation takes place. Whether this degradation will cause some of your page content to be lost to the browser, or whether the content of your page can still be accessed fully is dependent on whether the degradation is graceful.

The HTML standards were written with graceful degradation in mind- new attributes to older tags are safely ignored so that the rest of the tag can still function normally, and new tags are written with alternative display for browsers that don't support them in mind. There are many elements of HTML that can't be displayed or can be turned off in browsers that were written with the knowledge of these elements- such as images, javascript, and frames. Using the appropriate methods to provide an alternative message to those who can't see those elements or have turned them off is one way to design for graceful degradation.

If you design pages with graceful degradation in mind, by utilizing the built in elements of the HTML standards, and the advice provided here, you can design pages that should degrade gracefully in all browsers and are accessible.