The short answer

A, AA and AAA are the three conformance levels in the Web Content Accessibility Guidelines (WCAG). Level A is the minimum. Level AA is the standard most laws and policies require. Level AAA is the highest level.

Each level is a set of specific success criteria, and each higher level includes everything below it.

How the levels fit together

First, we must acknowledge that the levels stack. To claim AA, a page must meet every Level A criterion as well as every Level AA criterion. To claim AAA, it must meet all three sets, this means the website must meet Level A, Level AA and Level AAA.

WCAG 2.2 has 86 active success criteria:

Level A: 31 criteria

Level AA: 24 more (55 total for an AA claim)

Level AAA: 31 more (86 total for an AAA claim)

A few rules decide whether a claim holds up:

It's all or nothing. Missing one AA criterion means the page doesn't conform at AA. There's no "mostly AA."

Whole pages only.…