If you’re not familiar with Marco Zehe, you definitely should be. Marco, @MarcoInEnglish on Twitter, has done an incredible amount to ensure that Mozilla products and services are accessible. In whatever free time he has left over from that, he writes an informative blog often discussing the challenges faced in accessibility. In his most recent post, he discusses the basic things that all web developers should know when it comes to accessibility. Even if you’re not a developer, this is worth a read as it may provide you with terminology and a resource should you ever be in contact with one.

I’ve been asked again and again over the years what the absolute basics of web accessibility are. And while I always thought that it is not so difficult to find resources about these basics, …
Source: The web accessibility basics – Marco's Accessibility Blog