What in WCAG is required, and what is only advice

How WCAG is built, from its principles down to its techniques, which parts a page can fail, and what each version from 2.0 to 2.2 changed.

In short: Only the WCAG Recommendation is normative: its success criteria, at the level a policy picks, and its conformance requirements. Everything around them, Understanding, Techniques, the Quick Reference, ACT rules and the notes in the Recommendation itself, is informative advice.

When you need this

A team has rebuilt an online shop, and its contract asks for WCAG 2.1 Level AA. The audit comes back with six findings:

The newsletter form in the footer repeats the band's ids, and the report cites technique H93.
The phone field doesn't use technique G89.
Grey body text is 5.2:1, under the 7:1 that 1.4.6 asks for.
The help chatbot has no way to reach a person.
In a Windows contrast theme, the focus ring and the chosen size disappear.
The sign-up pop-up keeps Tab inside it and can't be closed from the keyboard.

The developers ask which of these the contract makes them fix. The answer depends on which parts of WCAG are requirements, at which level and in which version, and which parts are advice.

What can be tested: principles, guidelines and success criteria

WCAG 2.2 describes its guidance in layers ("WCAG 2 Layers of Guidance"). Only one of them is written to be tested:

Layer	In WCAG 2.2	Can a page fail it?
Principles	4: perceivable, operable, understandable, robust	No: they are the foundation
Guidelines	13	No: WCAG says "the guidelines are not testable"
Success criteria	86 (87 numbers; 4.1.1 is removed)	Yes, each at Level A, AA or AAA
Techniques and failures	In separate documents	No: they are informative

A success criterion is a testable statement, and WCAG's Understanding Conformance puts it plainly: in WCAG 2 the requirements are the success criteria. A criterion that doesn't apply to anything on the page is met. Beside the criteria, WCAG's section 5 sets five conformance requirements (the level, full pages, complete processes, accessibility support and non-interference), which are normative too; what it takes for a page to conform to WCAG explains them.

The numbers don't tell the level. Criteria added in 2.1 and 2.2 were put at the end of their guideline, so that older numbers didn't change, and WCAG 2.2 says the order "does not imply information about conformance level". Read the level printed on each criterion.

Levels A, AA and AAA

Each conformance level includes the ones below it: AA means every A and AA criterion, AAA means all three. Understanding Conformance lists what the Working Group weighed when it placed a criterion: whether assistive technology can work around a failure, whether the criterion can be met by all kinds of content, whether authors can learn it in a week's training or less, and whether it limits functionality or visual design. A criterion whose failure nothing can work around, and that any content can meet without special skills or a change of design, tends to be A; one that can't be met by every site, needs interpretation or changes the design a lot tends to be AAA.

Two points follow from the same document:

A level is not a severity. WCAG 2 "does not suggest any particular level of priority or severity", and how bad a failure is depends on how often it happens and on the content or function it affects. Which level to aim for is "fundamentally a policy decision".
AAA for a whole site is advised against. WCAG 2.2 §5.2.1, Note 2: "It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA success criteria for some content." Note 1 encourages reporting progress on criteria above the level reached.

That note is itself advice. WCAG 2.2 §5.1 says notes, examples, diagrams and sections marked non-normative are informative, even inside the Recommendation.

Required text and advice

W3C's page on the WCAG documents, The WCAG 2 Documents, says: "Only the WCAG technical standard includes requirements, which are normative." Everything else is informative, and the WCAG 2 FAQ adds that supporting documents "do not set or change requirements for WCAG". The normative text is the Recommendation's main content: the success criteria, the conformance section and the glossary definitions they use.

Document	Status	What it is for
WCAG 2.2 Recommendation	Normative, apart from its introduction, notes and examples	What a page must meet
Understanding WCAG 2.2	Informative	The intent of each criterion, who it helps, examples
Techniques for WCAG 2.2	Informative	Ways to meet a criterion, and documented failures
How to Meet WCAG 2.2 (Quick Reference)	Informative	The criteria and techniques, filtered by level, role or technology
ACT rules	Informative	Test rules for tools and test methods
Supplemental guidance	Informative	Advice beyond WCAG, much of it for cognitive and learning disabilities

Sufficient, advisory and failure techniques

Understanding Techniques sorts techniques into three kinds:

A sufficient technique is a reliable way to meet a criterion: used correctly, and accessibility supported for the content's users, it meets it. The converse doesn't hold. Content that doesn't use one hasn't failed, because there may be other ways to meet the criterion. Some are listed with AND, and then all of them are needed together.
An advisory technique improves accessibility but isn't counted as meeting a criterion: it may not cover all of it, rely on unstable technology, lack support, be untestable, or help some users while hurting others.
A failure is a documented way content fails a criterion, and it does fail it, "unless an alternate version is provided without the failure". They are particularly useful in an evaluation, because they do indicate non-conformance.

W3C "cautions against requiring W3C's sufficient techniques", and each technique's test is "only for a technique": failing it "does not necessarily mean failing WCAG".

The Working Group writes them. The WCAG 2 FAQ describes the steps: once a technology is stable, the group develops techniques, tests them with browsers and assistive technology, puts them out for public review, revises them and publishes them, which usually takes several months. Anyone can submit a technique on GitHub, and a failure found to be wrong can be reported, to be corrected or deleted.

WCAG 2 doesn't change; the techniques do, so they age. Their support notes name browser and screen reader versions that the group "may not update", and the Techniques change log lists the ones it has removed:

H45, longdesc, on 3 June 2022.
H93 (unique ids) and F77 (duplicate ids), in a batch of seven removed on 7 August 2024, after 4.1.1 Parsing was removed.
F4 and F47, failures for text-decoration: blink and the blink element, on 22 April 2025, when F112 (blinking for more than five seconds with no way to stop it) was added.

Check a technique's number against the current list before citing it, and cite the criterion it serves.

Versions, from 2.0 to WCAG 3

Each version is a W3C Recommendation at a dated address that never changes. As of 2 November 2026, the current one is WCAG 2.2, last updated on 12 December 2024; the WCAG 2 Overview lists any later update.

Version	Recommendation	What it changed
WCAG 2.0	11 December 2008	12 guidelines, 61 success criteria
WCAG 2.1	5 June 2018	Guideline 2.5 Input Modalities, and 17 criteria: 5 at A, 7 at AA, 5 at AAA
WCAG 2.2	5 October 2023, updated 12 December 2024	9 criteria: 2 at A, 4 at AA, 3 at AAA; 4.1.1 Parsing removed

The 17 criteria of 2.1 address mobile use, low vision, and cognitive and learning disabilities, among them 1.3.4 Orientation, 1.4.10 Reflow, 1.4.11 Non-text Contrast, 2.5.3 Label in Name and 4.1.3 Status Messages. The 9 of 2.2 are 2.4.11, 2.4.12 and 2.4.13 on focus, 2.5.7 Dragging Movements, 2.5.8 Target Size (Minimum), 3.2.6 Consistent Help, 3.3.7 Redundant Entry, and 3.3.8 and 3.3.9 on authentication.

The versions are built to be backwards compatible. WCAG 2.2 says content that conforms to it also conforms to 2.0 and 2.1, and later versions add criteria without changing the old ones. The one exception is 4.1.1 Parsing. WCAG 2.2 removes it because assistive technology no longer parses HTML itself, and the FAQ says problems it caught now "will fail other criteria, such as Info and Relationships (SC 1.3.1) or Name, Role, Value (SC 4.1.2)". Notes added to 2.0 (in its errata) and to 2.1 say 4.1.1 "should be considered as always satisfied for any content using HTML or XML", yet WCAG 2.2 also warns that authors held by policy to 2.0 or 2.1 "may need to continue to test and report 4.1.1".

The Working Group doesn't plan a WCAG 2.3. WCAG 3, the W3C Accessibility Guidelines, is a Working Draft (the latest dated 10 September 2026), and the WCAG 3 Introduction says it is "an incomplete draft that will change", with a different structure (guidelines written as outcomes, core and supplemental requirements, assertions) and a different conformance model. It "will not supersede WCAG 2", and WCAG 2 won't be deprecated for several years after WCAG 3 is finished. W3C's advice for now: meet WCAG 2.2. Check w3.org/WAI/wcag3 for its status.

What WCAG leaves out

WCAG 2.2 says that even AAA content "will not be accessible to individuals with all types, degrees, or combinations of disability, particularly in the cognitive, language, and learning areas", and that criteria for those areas were hard to agree on and test. Some of what's left out:

Still patterns that seem to move. Guideline 2.3's criteria cover flashes, defined as "a pair of opposing changes in relative luminance", and animation set off by interaction (2.3.3, AAA). A still pattern of high-contrast stripes that seems to shimmer, called pseudomotion, changes nothing over time, so it is neither.
Font weight and typefaces. Contrast is measured from the colours. Weight counts only in the definition of large-scale text, 14 point bold, and a note there says fonts with "extraordinarily thin strokes or unusual features" are harder to read at lower contrast. Understanding 1.4.3 advises choosing a heavier font or more contrast than required. No 2.2 criterion names a typeface; the WCAG 3 draft has one under development, "Text style readable (minimum)". A typeface so ornate that it acts as a graphic counts as non-text content under 1.4.11.
Cognitive load. Plain language is AAA (terms and policies with no plain-language summary, 3.1.5; jargon and unusual words with no definition, 3.1.3), and much of the rest is in the supplemental guidance's design patterns, such as "Avoid Too Much Content" and "Provide Human Help". Help chatbots with no way to reach a person is one: 3.2.6, new in 2.2, only asks that help repeated across pages comes in the same order relative to the rest of each page, and its Understanding page says it doesn't require help at all.
Personalisation. WCAG asks that the purpose of fields collecting information about the user can be determined in code (1.3.5, AA), and of components, icons and regions (1.3.6, AAA), so that software can adapt a page. It doesn't ask a page to offer adaptation; W3C's WAI-Adapt specifications are working on that.
Contrast themes. High contrast mode hiding focus, icons and selections shows a page that passes 1.4.11 in its own colours and loses its focus ring under a Windows contrast theme.

A finding in one of these areas is a best practice, and a report should say so.

Worked example

The team sorts the six findings against WCAG 2.1 Level AA, the contract's target, reading each in the Recommendation rather than the technique the report cites:

Finding	What the source says	In the report as
Duplicate ids (H93)	H93 was removed in 2024; WCAG 2.1's note treats 4.1.1 as always met for HTML. In duplicate ids that point labels at the wrong field, the footer's field is left with no label, which fails 1.3.1 and 4.1.2	A failure of 1.3.1 and 4.1.2, not of H93
Phone field without G89	G89 is one sufficient technique for 3.3.2. The field has a label, so it meets 3.3.2; input masks that change a typed or pasted number is a best practice	Best practice
Body text at 5.2:1	1.4.6 is AAA. 1.4.3 (AA) asks for 4.5:1, and 5.2:1 meets it	Beyond the target
No way to reach a person	3.2.6 is new in 2.2, so outside a 2.1 contract, and it doesn't require help anyway	Best practice
Focus lost in a contrast theme	The page meets 1.4.11 in its own colours	Best practice
Pop-up keeps Tab inside	2.1.2 is Level A, and applies to everything on the page	A failure

Result: two failures to fix under the contract, one item beyond its level, and three best practices, each reported as what it is. The team plans to move to WCAG 2.2, as W3C recommends, and finds 3.2.6 met already: the chatbot sits in the same corner of every page.

Common mistakes

Writing a technique into a contract as the requirement. W3C cautions against it: it rules out other ways to meet the criterion, and newer technology. Name the criteria. Understanding Techniques explains why.
Reporting a failed technique test as a failed criterion. The test checks the technique, not WCAG. Judge the criterion itself, as input masks that change a typed or pasted number does: its phone field meets 3.3.2 through its label, and the mask still changes the number.
Ranking findings by level. WCAG says levels are not severity: a Level AA failure can block a task that a Level A one only slows. Which findings to fix first, and when to rebuild instead ranks them by what each does to the task.
Asking for AAA across a site. WCAG advises against it, because some content can't meet every AAA criterion. Set AA, and add the AAA criteria that fit, as what it takes for a page to conform to WCAG explains.
Citing a removed technique. H93, F77 and H45 are gone. A duplicate id is reported under the criterion it breaks, as in duplicate ids that point labels at the wrong field.
Dropping 4.1.1 where a policy still names 2.0 or 2.1. WCAG 2.2 warns that such authors may need to test and report it. Check what the policy asks.
Calling a best practice a failure. A report that does loses trust. Say what a person meets and that no criterion requires the fix, as high contrast mode hiding focus, icons and selections and help chatbots with no way to reach a person do.
Waiting for WCAG 3. It is a draft that will change; W3C advises meeting WCAG 2.2 now.

What the standard says

Required (WCAG 2.2, normative):

§5.1: "The main content of WCAG 2.2 is normative and defines requirements that impact conformance claims. Introductory material, appendices, sections marked as 'non-normative', diagrams, examples, and notes are informative (non-normative)."
§5.2.1: for Level AA conformance, "the web page satisfies all the Level A and Level AA success criteria, or a Level AA conforming alternate version is provided."

Advice (informative):

WCAG 2.2 Introduction, "WCAG 2 Layers of Guidance": "The guidelines are not testable", and the techniques "are informative".
WCAG 2.2 §5.2.1, Note 2: Level AAA "is not recommended" as a general policy for entire sites.
Understanding Techniques: "Techniques are informative — that means they are not required. The basis for determining conformance to WCAG 2.2 are the success criteria from the WCAG 2.2 standard — not the techniques."

The standards built on WCAG name different versions:

Section 508 (E205.4) requires WCAG 2.0 Level A and AA success criteria and conformance requirements.
EN 301 549 V3.2.1 (clause 9) uses WCAG 2.1 Level AA. Clause 9.5 encourages the AAA criteria where they can be applied, and quotes WCAG's note against requiring AAA for whole sites.
JIS X 8341-3:2016 is identical to ISO/IEC 40500:2012, that is, WCAG 2.0: 61 criteria, 4.1.1 among them. WAIC, the committee drafting its revision, expects a revision based on the September 2025 ISO edition in 2027, or 2028 at the latest. The 2024 edition of the Ministry of Internal Affairs and Communications' guideline for public websites asks new public sites to follow WCAG 2.2's criteria where they can.

Limits

This page explains how WCAG is put together. It doesn't settle which version and level a contract, a law or a policy requires: that is in the document itself, and when it is unclear, the client or a lawyer decides. Whether a finding fails a criterion is the tester's judgement, made against the criterion's text and its Understanding document. Version dates and the WCAG 3 draft are as of 2 November 2026; check the WCAG 2 Overview and the WCAG 3 Introduction for anything newer. What a page needs to conform, and what can be claimed, is in what it takes for a page to conform to WCAG.

Terms

success criterion: A testable statement in WCAG, at Level A, AA or AAA. The success criteria are what a page conforms to.
conformance level: A, AA or AAA. Each level includes every criterion of the levels below it.
normative: Text that sets a requirement. In WCAG 2, only the Recommendation's main content is normative.
informative: Text that explains or advises without setting a requirement: Understanding, Techniques, the Quick Reference, ACT rules, and the notes and examples inside the Recommendation.
sufficient technique: A documented way to meet a success criterion. Used correctly, and accessibility supported, it meets the criterion; not using it doesn't mean failing.
advisory technique: A documented way to improve accessibility that isn't enough, or isn't reliable enough, to count as meeting a criterion.
failure: A documented way content fails a success criterion, unless a conforming alternate version is provided.

Sources and guides

Guides that show it

This page explains a practice, with recreated examples. It is not legal advice, and it is not a finding about a named client.