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WCAG 2.1 Explained

Understand web accessibility guidelines in plain language. Learn what WCAG means for your website.

What is WCAG?

WCAG stands for Web Content Accessibility Guidelines. It's an international standard developed by the W3C (World Wide Web Consortium) that explains how to make web content accessible to people with disabilities.

The current version is WCAG 2.1, released in 2018. It builds on WCAG 2.0 with additional criteria for mobile accessibility, cognitive disabilities, and low vision.

WCAG is the standard referenced by most accessibility laws worldwide, including the European Accessibility Act (EAA).

Conformance levels: A, AA, AAA

WCAG has three levels of conformance. Each level adds more criteria on top of the previous.

A

Level A (Minimum)

The bare minimum for accessibility. Addresses the most critical barriers. Without Level A, many users with disabilities cannot use the website at all.

Examples: text alternatives for images, keyboard navigation, no keyboard traps

AA

Level AA (Recommended)

Required by EAA

The standard most laws require, including the EAA. Addresses major barriers that affect a significant number of users.

Examples: color contrast ratios, captions for videos, consistent navigation

AAA

Level AAA (Enhanced)

The highest level of accessibility. Not required by law and not always achievable for all content types, but provides the best experience.

Examples: sign language for videos, enhanced contrast, no timing limits

The 4 principles (POUR)

WCAG is organized around four fundamental principles. Content must be:

Perceivable

Users must be able to perceive the content. This means providing alternatives for non-text content like images and video.

Alt text for images
Captions for videos
Sufficient color contrast

Operable

Users must be able to operate the interface. Not everyone uses a mouse—keyboard and assistive tech users need full access.

Keyboard navigation
Skip navigation links
Visible focus indicators

Understandable

Content and navigation must be understandable. Users should be able to comprehend information and predict how the site works.

Clear language
Form labels and instructions
Helpful error messages

Robust

Content must be robust enough to work with current and future technologies, including assistive technologies.

Valid HTML
Proper ARIA usage
Screen reader compatible

Top 10 common WCAG failures

These are the most frequent issues we find when scanning websites:

1

Missing alt text on images

Screen reader users can't understand images

2

Insufficient color contrast

Hard to read for low vision users

3

Missing form labels

Users don't know what to enter in fields

4

Empty links or buttons

No context about where links go

5

Missing document language

Screen readers use wrong pronunciation

6

Non-descriptive link text

"Click here" doesn't explain the destination

7

Missing focus indicators

Keyboard users can't see where they are

8

Improper heading structure

Hard to navigate and understand content

9

Missing video captions

Deaf users can't access audio content

10

Keyboard traps

Users get stuck and can't navigate

A note on accessibility overlays

Some companies sell "overlay widgets" that claim to make your website accessible automatically. These don't work and can actually make things worse.

Cannot fix underlying code issues
Often interfere with assistive technologies
Have been rejected by major disability advocacy groups
Do not provide legal protection from lawsuits

The only way to truly become accessible is to fix the issues in your website's code.

Why WCAG compliance matters

Beyond doing the right thing, WCAG compliance has tangible business benefits.

Avoid EAA penalties

The European Accessibility Act requires WCAG 2.1 AA compliance. Non-compliance can result in fines up to €500,000+, market restrictions, and legal action.

EAA requirements

Boost your SEO

WCAG-compliant websites gain 37% more organic traffic and rank for 27% more keywords. Google's Core Web Vitals align with accessibility.

SEO benefits research