what are the 3 levels of w3c wai accessibility guidelines?
They have 12-13 guidelines that are organized under 4 principles: perceivable, operable, understandable, and robust. For each guideline, there are testable success criteria, which are at three levels: A, AA, and AAA. For a short summary of the WCAG 2 guidelines, see WCAG 2.1 at a Glance.