1.2.3 The Levels of WCAG 2.0

A three-level pyramid being used to indicate the 3 accessibility levels of  WCAG 2.0.

An important concept adopted by WCAG 2.0 is its three "levels" of conformance called Level A, Level AA and Level AAA (or single A, double A, triple A, respectively). Typically, an organization will strive for its web content to achieve compliance with one of the levels; Level A being basic accessibility and Level AAA the highest. WCAG 2.0 categorizes the levels as follows:

Level A: If web content does not meet all the requirements for Level A, then some or all of it will be completely inaccessible to some segment of the population.

Level AA: If web content meets Level A, but not Level AA, then some or all of the content will be difficult for some people to use.

Level AAA: Meeting all the requirements for Level AAA would mean the content is as accessible as possible given the current state of web and end-user technology.

Each success criteria listed in the guidelines is associated with one of these three levels of accessibility. In order to claim compliance at any level, ALL of the relevant requirements for that, and any lower levels, must be satisfied. Refer also to Section 6.0 — Resources.