Accessibility is something that is rarely taken seriously and something most business owners are unaware of. By accessibility we mean your website being displayed properly to anyone and everyone that comes across your website, including the disabled. The FAE (Functional Accessibility Evaluator) is a great online validation tool that combines the validation from the W3C (World Wide Web Consortium) Guidelines, the United States Federal Government Electronic and Information Technology Accessibility Standards (Section 508), and the Illinois Information Technology Accessibility Act (IITAA).
Some people would argue that it “takes too much time,” or “something they will do later” — but the fact of the matter is, your website should not ignore anyone. By creating a website that is completely accessible to anyone, you are entering into Universal Design. Last time you walked into a supermarket, did you realize the doors (most likely) opened up automatically for you? That function was originally designed to assist those in wheelchairs to enter the store more easily, while also helped anyone that was not disabled to enter the store easily too (while also reducing germs etc).
When you create a website that is accessible to the entire population, you are also enabling your website to be more search engine friendly, while also helping you become a better programmer / designer (three birds + , one stone).
Sources:
FAE (Functional Accessibility Evaluator)
W3C (World Wide Web Consortium) Guidelines
the United States Federal Government Electronic and Information Technology Accessibility Standards (Section 508)
Illinois Information Technology Accessibility Act (IITAA)
Great book for anyone wanting to expand their knowledge on Web Standards or Accessibility:
Designing With Web Standards – Jeffrey Zeldman