Guide 01 · Standards
WCAG A, AA and AAA.
Three conformance levels, one of which matters in practice. Here is what each one covers and why nearly every regulator, procurement rule and settlement agreement lands on the middle one.
What WCAG is.
The Web Content Accessibility Guidelines are a technical standard published by the World Wide Web Consortium, the body that maintains the standards the web runs on. WCAG 2.2 is the current version, published as a W3C Recommendation in October 2023. It is free to read and has been publicly available in some version since 1999.
WCAG is not a law. It is the measure that laws, regulations, procurement rules and settlement agreements point at when they need to define what accessible means. That distinction matters: a business does not violate WCAG, it fails to meet it, and whether that failure carries legal consequence is a separate question.
Four principles
Every requirement in WCAG sits under one of four principles. Content must be:
- Perceivable — a person can take the information in, whether they see it, hear it, or read it by touch.
- Operable — a person can work the controls, including without a mouse.
- Understandable — the content and the interface behave predictably.
- Robust — assistive technology can interpret the page reliably.
Under those principles sit individual success criteria, each written to be testable and each assigned a conformance level.
A, AA and AAA.
The levels are not a quality score. They describe how essential a criterion is and how broadly it can reasonably be applied.
| Level | What it covers | In practice |
|---|---|---|
| A | The floor. Failing these makes content impossible to use for some people rather than merely difficult. Text alternatives for images, keyboard operability, no keyboard traps. | Necessary and nowhere near sufficient. A site can meet every Level A criterion and still be unusable. |
| AA | Everything in A, plus the criteria that address the barriers most people actually encounter. Color contrast minimums, visible focus indicators, consistent navigation, meaningful headings and labels. | The operative level. This is what regulators adopt, what procurement requires, and what settlement agreements specify. |
| AAA | Everything in AA, plus enhancements: higher contrast ratios, sign language for prerecorded audio, reading level limits. | Not intended as a site-wide target. W3C states directly that AAA conformance is not recommended as a general policy for entire sites, because some content cannot satisfy every AAA criterion. |
Why AA is the answer to almost every question
When a US federal agency, a state procurement office, a university or a court-approved settlement needs to define accessible, it has consistently pointed at Level AA. The Department of Justice adopted WCAG 2.1 Level AA as the technical standard for state and local government websites in its 2024 Title II rule. Section 508 procurement standards point at Level AA. Settlement agreements in web accessibility matters routinely specify it.
If someone asks what standard a business should meet, the answer is WCAG 2.2 Level AA unless a specific rule says otherwise.
Where sites actually fail.
A small number of criteria account for a large share of real barriers. These are the ones that appear again and again:
- 1.1.1 Non-text Content (A) — images carrying information with no text alternative. A screen reader announces nothing, or announces a filename.
- 1.4.3 Contrast, Minimum (AA) — text too faint against its background. Affects far more people than any other single criterion, including anyone reading in sunlight.
- 2.1.1 Keyboard (A) — a control that only responds to a mouse. Date pickers and custom dropdowns are the usual offenders.
- 2.4.7 Focus Visible (AA) — the outline showing where you are has been removed for aesthetic reasons, leaving keyboard users lost.
- 4.1.2 Name, Role, Value (A) — a styled <div> used as a button. It looks like a control and is invisible to assistive technology.
The last one is worth dwelling on. It is the most common way a checkout, a booking or a payment becomes impossible to complete, and it is invisible to everyone who tests with a mouse and working eyes. Nobody at the business ever sees it.
Automated checks find a minority of barriers.
No tool can determine whether alternative text is accurate, whether a heading structure is meaningful, or whether an error message is understandable. Automated evaluation reliably catches things like missing alternative text, insufficient contrast and absent form labels. It cannot catch most of what is left.
This cuts both ways, and honest work says so. A page with zero automated failures has not been shown to be accessible. And a report consisting only of automated output has not established anything a person confirmed.
What makes a finding defensible covers that distinction properly.
Read the primary sources.
- WCAG 2.2 quick reference — every success criterion, filterable by level.
- W3C WAI on WCAG — the standard and its supporting documents.
- ADA.gov — Department of Justice guidance and rulemaking.
This guide explains a published technical standard. It is general information and not legal advice, and it does not address how any law applies to a particular business. Aldermarq is not a law firm.