Guides › WCAG 2.1 Level AA in plain English

WCAG 2.1 Level AA in plain English

12 min read Reviewed 2026-08-22

WCAG is organised as four principles, thirteen guidelines and fifty success criteria at Levels A and AA. Here is what each one means without the specification language.

What the levels mean

Level A is the floor: fail these and some people simply cannot use your service. Level AA is the conformance target for essentially all legislation, including EN 301 549 and therefore the EAA. Level AAA exists, is not required, and in some cases is not achievable for all content — nobody is asking you to meet it.

Conformance is all-or-nothing per page: to claim Level AA, a page must satisfy every A and AA criterion that applies to it.

Perceivable

Users must be able to perceive the information, through whichever sense they rely on. It is the principle this site is named after, and the one that fails most often.

• 1.1.1 Non-text Content (A) — Every image, icon and chart has a text alternative that conveys the same information. Decorative images are explicitly marked as decorative.
• 1.2.1–1.2.5 Time-based Media (A/AA) — Prerecorded video needs captions and audio description. Live video needs captions. Audio-only content needs a transcript.
• 1.3.1 Info and Relationships (A) — Structure conveyed visually must also exist in the markup. A heading looks like a heading and is a heading element.
• 1.3.2 Meaningful Sequence (A) — Reading order in the DOM matches the visual order.
• 1.3.3 Sensory Characteristics (A) — Instructions do not rely solely on shape, size or position. Not "click the round button on the right".
• 1.3.4 Orientation (AA) — Do not lock to portrait or landscape without good reason.
• 1.3.5 Identify Input Purpose (AA) — Common fields carry the right autocomplete token so browsers can autofill them.
• 1.4.1 Use of Color (A) — Colour is never the only way information is conveyed. A red border alone does not communicate an error.
• 1.4.2 Audio Control (A) — Audio that plays automatically for more than three seconds must be stoppable.
• 1.4.3 Contrast (Minimum) (AA) — 4.5:1 for body text, 3:1 for large text. The single most commonly failed criterion on the web.
• 1.4.4 Resize Text (AA) — Text scales to 200% without loss of content or function.
• 1.4.5 Images of Text (AA) — Use real text rather than pictures of text.
• 1.4.10 Reflow (AA) — Content works in a 320 CSS pixel wide viewport without horizontal scrolling.
• 1.4.11 Non-text Contrast (AA) — Interface components and focus indicators need 3:1 against what is adjacent. Faint grey input borders commonly fail this.
• 1.4.12 Text Spacing (AA) — Nothing breaks when the user increases line height, letter spacing or word spacing.
• 1.4.13 Content on Hover or Focus (AA) — Tooltips and popovers can be dismissed, hovered over, and stay visible until dismissed.

Operable

Users must be able to operate the interface, whatever device they drive it with.

• 2.1.1 Keyboard (A) — Everything works from a keyboard alone. Test this today; it takes five minutes and tells you more than any report.
• 2.1.2 No Keyboard Trap (A) — Focus can always move back out of a component. Modals are the usual offender.
• 2.1.4 Character Key Shortcuts (A) — Single-character shortcuts can be turned off or remapped.
• 2.2.1 Timing Adjustable (A) — Time limits can be extended or turned off. Session timeouts in checkout matter here.
• 2.2.2 Pause, Stop, Hide (A) — Anything moving, blinking or auto-updating for more than five seconds can be paused. Carousels.
• 2.3.1 Three Flashes (A) — Nothing flashes more than three times per second. This one is a seizure risk, not an inconvenience.
• 2.4.1 Bypass Blocks (A) — A skip link or proper landmarks, so keyboard users are not tabbing through the nav on every page.
• 2.4.2 Page Titled (A) — Every page has a unique descriptive title.
• 2.4.3 Focus Order (A) — Tab order follows a logical, meaningful sequence.
• 2.4.4 Link Purpose (A) — Link text says where it goes. Twelve links all reading "read more" fail.
• 2.4.5 Multiple Ways (AA) — More than one route to each page: navigation, search, or a sitemap.
• 2.4.6 Headings and Labels (AA) — Headings and labels describe their content.
• 2.4.7 Focus Visible (AA) — The focus indicator is always visible. Never outline: none without a replacement.
• 2.5.1 Pointer Gestures (A) — Anything needing a multi-point or path-based gesture has a simple single-pointer alternative.
• 2.5.2 Pointer Cancellation (A) — Actions fire on release, not on press, so a mis-tap can be aborted.
• 2.5.3 Label in Name (A) — The accessible name contains the visible label text, so voice control users can say what they see.
• 2.5.4 Motion Actuation (A) — Shake-to-undo and similar have a conventional alternative.

Understandable

• 3.1.1 Language of Page (A) — <html lang="sv">. One attribute.
• 3.1.2 Language of Parts (AA) — Passages in another language are marked up as such.
• 3.2.1 On Focus (A) — Focusing something does not change context unexpectedly.
• 3.2.2 On Input (A) — Changing a field value does not auto-submit or navigate without warning.
• 3.2.3 Consistent Navigation (AA) — Navigation appears in the same relative order across pages.
• 3.2.4 Consistent Identification (AA) — The same function is labelled the same way everywhere.
• 3.3.1 Error Identification (A) — Errors are described in text, and the field at fault is identified.
• 3.3.2 Labels or Instructions (A) — Every input has a label. Placeholders are not labels.
• 3.3.3 Error Suggestion (AA) — Where you know the fix, suggest it. "Date must be DD/MM/YYYY", not "invalid input".
• 3.3.4 Error Prevention (AA) — Legal, financial and data submissions are reversible, checked, or confirmed before they commit.

Robust

• 4.1.1 Parsing (A) — Historically about valid markup; obsoleted in WCAG 2.2 because modern browsers handle it. Duplicate id values are still worth fixing because they break label associations.
• 4.1.2 Name, Role, Value (A) — Every interactive element exposes what it is, what it is called and what state it is in. This is the criterion behind most custom-component failures, and the main reason to prefer native HTML elements over rebuilt ones.
• 4.1.3 Status Messages (AA) — Messages that appear without a page reload are announced to assistive technology. "3 items added to cart", validation summaries, live search result counts.

Test your site against these criteria free →

Last reviewed 2026-08-22. Summaries are simplified for readability; the normative text is published by the W3C.