Web Content Accessibility Guidelines (WCAG)
The Web Content Accessibility Guidelines (WCAG) are a list of criteria your website or mobile application need to meet in order to be legally compliant.
In order for your website or application to be legally compliant, it needs to meet the level of AA. This is outlined in the accessibility regulations.
WCAG 2.1 is a list of criteria. Each one is specifically designed to consider a particular need, but will fit into one of the following 4 categories:
The criteria make up 3 levels. A, AA and AAA. The levels build on one another, so to be AA compliant you need to meet all of the A and AA criteria. For A and AA there are around 50 criteria in total.
You can find a list of all the A and AA criteria you need to meet in the W3C WCAG 2.1 QuickRef guide.
Full AAA compliance is not recommended as a general policy. It is not always possible to satisfy all of the criteria, and doing so will make your service appear inconsistent with the rest of GOV.UK.
You should understand the WCAG 2.1 AAA criteria and choose those which apply to your content and will have a positive impact on your users.