Web accessibility can be defined as:

an approach to web design that aims to ensure the widest access to the content and features of a website. The term is often used to refer to accessibility for people with disabilities, particularly blindness. (source)

However accessibility is also about making Web content more available to all users:

whatever user agent they are using (e.g., desktop browser, voice browser, mobile phone, automobile-based personal computer, etc.) or constraints they may be operating under (e.g., noisy surroundings, under- or over-illuminated rooms, in a hands-free environment, etc.).

While we (surprisingly) seldom see accessibility issues discussed in SEO community, search engine optimizers should definitely both explore and implement accessibility standards

(more…)