Glossary · Accessibility term

Technique

A technique is one of the W3C's documented ways of meeting, or of failing, a WCAG rule. Each one carries an ID whose letter says which technology it is for, so H is HTML, C is CSS, F is a documented failure, and G is general, meaning it holds whatever you built the page in rather than pointing at particular code. They come in three kinds. A sufficient technique is a documented way of meeting a criterion, though not always alone, because W3C joins some of them with AND and then the whole set is the route. An advisory technique goes past what a criterion requires, or covers only part of one, or uses something support has not caught up with. And a failure describes a particular way of getting it wrong. W3C publishes 432 of them for WCAG 2.2 across all three levels, and we have explained every one. The thing to hold on to is that all three kinds are informative. Content can satisfy WCAG without using a single documented technique, so an auditor who fails you for not using a named one has confused the advice with the rule.

In practice

A failure is not simply the negation of a sufficient technique, and that catches people reading a report. Finding a documented failure pattern in your code is evidence of a problem rather than an automatic finding. Content can still satisfy the criterion if it offers equivalent alternative content or functionality that does. The same logic runs the other way. You can meet a criterion any way that works, and the techniques exist because most people would rather be shown a known-good route than invent one.

Advisory is a stronger category than the name suggests. W3C's own description is that advisory techniques may be the only way some users can access some kinds of content, and that some of them address barriers no testable criterion covers at all. That is the standards body saying, in its own documentation, that conformance and accessibility are not the same thing, and it is the best-sourced argument there is for auditing past the checklist.

The library moves independently of the standard. The techniques index carries its own date and is revised between WCAG versions, so any count is a count on the day it was taken. Old lists also carry techniques for technologies nobody uses any more.

On what a machine can check, be careful whose number you are quoting. W3C publishes nothing that splits its techniques this way. Our own technique-by-technique classification grades 356 of the 432 and puts 10 of those as fully machine-checkable, 228 as partly checkable, and 118 as human-only. The 432 is W3C's. Every other number in that sentence is ours, and anybody quoting it back at you as a W3C figure has got it from us.

Why it matters

Techniques are where the practical advice lives. A criterion tells you ordinary body text needs a contrast ratio of 4.5:1. The techniques tell you how to reach it, and the failure documents tell you what people get wrong on the way. Each one also carries a test procedure, which is a large body of published testing method most teams never open and could be running this week. Their informative status is what protects you in a review, because the thing you have to meet is the criterion and never the route somebody expected you to take.

Reading the ID in your report

The letter tells you which technology the technique is for. H is HTML, C is CSS, G is general, ARIA is ARIA, SCR is script, PDF is PDF, and F is a documented failure. So an F number in a report is telling you somebody found a known-bad pattern, and an H or G number is telling you a known-good one was expected. Neither is the rule. The rule is the criterion the report cites beside it.

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