Success criterion

In practice

The number tells you where it sits and nothing about how hard it is. Principle, then guideline, then position, so 1.4.3 is the third criterion under the fourth guideline of the first principle. What the position does not tell you is the level, and that trips people who scan a list. Criteria added in 2.1 and 2.2 were appended to the end of their guideline rather than slotted in by level. So guideline 2.5 has a Level AAA criterion sitting ahead of two Level AA ones. Only the level marker on the criterion itself is telling you anything.

Criteria state outcomes, not methods. Ordinary body text needs a contrast ratio of at least 4.5:1, with large text, incidental text and logotypes carved out, and the rule says nothing at all about how you get there. The how lives in the techniques underneath, and the whole technique layer is informative. Be careful with the word advisory there. W3C uses it for one specific kind of technique alongside sufficient ones and failures, so calling the whole layer advisory starts an argument in an audit review.

Passing all 55 is not the whole of conformance, and this is where claims come unstuck. Five conformance requirements have to hold together. A page conforms whole or not at all. A process, like a checkout, has to conform end to end. You have to be relying only on ways of using your technologies that assistive technology actually supports. And content you are not relying on still cannot get in the way of the rest.

Why it matters

Conformance is decided against criteria and the five requirements printed beside them, which is why WCAG 2.2 AA in a contract means 55 named rules applied to the pages in scope rather than a general impression. Not all 55 are one test each. Several carry exceptions and several apply only in particular conditions, so what you run is more like a decision tree than a tick list. It is also why a supplier who answers a question about a principle has answered nothing. One footnote for anybody quoting numbers. We have not found a headline count published by W3C, so both 55 and 86 are derived by adding the criteria up, which everybody does the same way.

Where this shows up on the site

• All 55 rules, explained
• All 55 rules, listed

Related terms

• WCAGWCAG is the international standard for web accessibility, published by the W3C.
• Level A, AA, AAALevel A, AA and AAA are WCAG's three conformance levels, and they stack.
• GuidelineA guideline is the middle layer of WCAG, and WCAG 2.2 has 13 of them sitting between the four principles and the rules anybody is ever tested against.
• TechniqueA technique is one of the W3C's documented ways of meeting, or of failing, a WCAG rule.
• ConformanceConformance means satisfying all the requirements of a standard, and WCAG has five of them rather than one.
• POURPOUR is the field's shorthand for WCAG's four principles, which are Perceivable, Operable, Understandable and Robust.