The goal of web accessibility is to ensure that people with disabilities can use the web in equal conditions than others. In the field of OER, accessibility is twofold, the websites and the educational resources. Accessibility is the primary requirement to guarantee equal access to all users, especially, people with disabilities.
The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI) released in 2008 the Web Content Accessibility Guidelines (WCAG) 2.0. The WCAG 2.0 is a stable, referenceable technical standard that was approved as an ISO/IEC 40500 international accessibility standard in October 2012.
This standard defines a broad range of recommendations for making Web content more accessible to a wider range of people with disabilities. Accessibility involves disabilities such as visual (blindness and low vision), auditory (deafness and hearing loss), motor (limited movement of upper limbs), cognitive limitations, and learning disabilities.
This standard contains a set of twelve guidelines organized under four principles:
These guidelines are based on a set of success criteria written as testable statements that are not technology-specific. Each of them is associated with a level of conformance A, AA, and AAA. The levels A and AA are mandatory while AAA is desirable.
The evaluating of web accessibility can be carried out with software evaluation tools for a preliminary analysis. These automated tools have distinct coverage, completeness, and correctness concerning to WCAG 2.0, whereby, it is recommendable to use a combination of some automated tools in web accessibility analysis to achieve reliable evaluation.
A formal validation should be complement with a human expert to verify and interpret the results. Complementary it is important to conduct heuristic accessibility evaluation based on specific conditions of impairments, and complement with user testing.