The Americans with Disabilities Act (ADA) is a piece of legislation designed to ensure that differently-abled people are properly equipped to navigate the same things that everyone else enjoys. Just as you wouldn’t build a shopping center without an alternative to stairs, so ADA standards require that websites are configured in such a way that someone who is hearing-impaired, or sight-impaired, etc., is not summarily excluded from using a public website.
Building a website so that it conforms to ADA standards is largely a matter of putting yourself in that other person’s place and anticipating what they’re going to need, then meeting that need. This includes such thoughtful details as a description of each graphic (within its “alt” tag) so that a sight-impaired person may be able to use an electronic reader to understand the contents of the missing graphic. Other standard considerations include offering a web-based alternative to PDF files since most electronic “screen readers” cannot make out the contents of PDF files. Other significant elements that can hinder a differently-abled person include improperly designed frames, and websites that rely primarily or exclusively on Flash animations, with little or no text.
By conforming to ADA standards, you are enabling visitors from all walks of life, and simultaneously enabling visitors with different hardware and software capabilities to view and use your site. Since some visitors will be limited to viewing your site as a text-only site, or on a tiny Blackberry screen, or using a very slow dial-up connection, it’s important to anticipate the uniqueness of each visitor’s situation and to provide reasonable access alternatives for them.
If you’d like to see, first-hand, what a person experiences when they are limited to a text-only browser, try visiting seebot.org and typing your web address in the search box. The results can be very revealing.