WCAG 2.0 vs 2.1 vs 2.2: How the Standard Has Evolved

The Web Content Accessibility Guidelines have been refined through several major versions, each expanding the scope of accessibility to address emerging technologies, newly understood barriers, and evolving user needs. Understanding the differences between versions is important for knowing which standard applies to your organization and what you need to do to stay current.

WCAG 2.0 (December 2008)

WCAG 2.0 was a landmark publication that fundamentally reshaped how the world approaches digital accessibility. It introduced the four POUR principles (Perceivable, Operable, Understandable, Robust), the three-level conformance system (A, AA, AAA), and technology-neutral success criteria that could apply to any web technology rather than being tied to specific markup languages.

WCAG 2.0 contains 61 success criteria: 25 at Level A, 13 at Level AA, and 23 at Level AAA. It remains a W3C Recommendation and is still referenced by some legislation, including Section 508 of the US Rehabilitation Act.

The strengths of WCAG 2.0 were its technology neutrality and its structured approach to testable requirements. However, it was developed before smartphones and tablets became primary computing devices, and it did not adequately address mobile accessibility, low vision beyond magnification, or cognitive disabilities.

WCAG 2.1 (June 2018)

WCAG 2.1 was developed to fill the gaps that had become apparent in the decade since WCAG 2.0. It added 17 new success criteria — 5 at Level A, 7 at Level AA, and 5 at Level AAA — bringing the total to 78.

The new criteria addressed three primary areas:

Mobile accessibility — Criteria such as Orientation (1.3.4), which prevents locking content to a single display orientation, and Pointer Gestures (2.5.1), which requires single-pointer alternatives to complex gestures like pinch-to-zoom.

Low vision — Criteria such as Reflow (1.4.10), requiring content to work at 320px width without horizontal scrolling, Text Spacing (1.4.12), and Content on Hover or Focus (1.4.13).

Cognitive and learning disabilities — Criteria such as Identify Input Purpose (1.3.5), enabling autocomplete for user information fields, and several input assistance criteria.

WCAG 2.1 is backward compatible with WCAG 2.0 — content that conforms to 2.1 also conforms to 2.0. It is currently referenced by the ADA Title II rule, EN 301 549, and is the baseline for EAA compliance through the harmonized European standard.

WCAG 2.2 (October 2023)

WCAG 2.2 is the current version and the one organizations should target. It adds nine new success criteria and removes one that became obsolete, bringing the total to 86 criteria: 32 at Level A, 24 at Level AA, and 30 at Level AAA.

The removed criterion is 4.1.1 Parsing, which originally required valid HTML to prevent assistive technology parsing issues. Modern browsers and assistive technologies now handle parsing robustly, making this criterion unnecessary.

The nine new criteria in WCAG 2.2 are:

2.4.11 Focus Not Obscured – Minimum (Level AA) — When a component receives keyboard focus, it must not be entirely hidden behind other content such as sticky headers, cookie banners, or chat widgets.

2.4.12 Focus Not Obscured – Enhanced (Level AAA) — The focused component and its focus indicator must be fully visible, with no part hidden by other content.

2.4.13 Focus Appearance (Level AAA) — Focus indicators must be at least a 2-pixel wide perimeter of the unfocused component and have at least 3:1 contrast between focused and unfocused states.

2.5.7 Dragging Movements (Level AA) — Any functionality that requires dragging (such as reordering a list or adjusting a slider) must also be achievable through a single-pointer alternative like clicking or tapping.

2.5.8 Target Size – Minimum (Level AA) — Interactive targets must be at least 24x24 CSS pixels, or have sufficient spacing from other targets. This is a relaxed version of the existing AAA criterion 2.5.5 Target Size Enhanced (44x44 pixels).

3.2.6 Consistent Help (Level A) — If help mechanisms (contact information, help links, chat support) appear on multiple pages, they must appear in the same relative position on each page.

3.3.7 Accessible Authentication – Minimum (Level AA) — Authentication processes must not require cognitive function tests (such as remembering a password or solving a puzzle) unless an alternative method is available or assistance mechanisms are provided. Object recognition tests (like selecting images of traffic lights) are permitted at this level.

3.3.8 Accessible Authentication – Enhanced (Level AAA) — Same as 3.3.7 but without the exception for object recognition and user-provided content.

3.3.9 Redundant Entry (Level A) — Information that a user has already entered in a multi-step process must be auto-populated or available for selection rather than requiring the user to re-enter it.

Backward Compatibility

All WCAG 2.x versions are backward compatible. Content conforming to WCAG 2.2 also conforms to 2.1 and 2.0. This means you can target WCAG 2.2 with confidence that you are meeting the requirements of older versions still referenced by some legislation.

What About WCAG 3.0?

The W3C is developing a new major version of the accessibility guidelines, currently called W3C Accessibility Guidelines (WCAG 3.0). This version will represent a more fundamental restructuring, with a new conformance model, broader scope beyond web content, and different scoring mechanisms. However, WCAG 3.0 is still in early development and is not expected to become a W3C Recommendation for several years. Organizations should focus on WCAG 2.2 AA as the current target.