← Go Back

WCAG (Web Content Accessibility Guidelines)

What is WCAG?

WCAG (Web Content Accessibility Guidelines) are a set of internationally recognized standards developed by the Web Accessibility Initiative (WAI) of the World Wide Web Consortium (W3C). These guidelines provide a comprehensive framework for making web content more accessible to people with disabilities, including visual, auditory, physical, speech, cognitive, language, learning, and neurological disabilities.

Think of WCAG like a blueprint for building websites that work for everyone. Just as building codes ensure buildings are safe and accessible to people with different abilities, WCAG ensures websites are accessible to people with different abilities. It's not just about compliance - it's about creating digital experiences that truly work for all users.

The guidelines are designed to be technology-agnostic, which means they can be applied to websites, applications, and digital content regardless of the technologies used to create them. WCAG serves as the primary global standard for web accessibility and has been adopted by many governments and organizations worldwide as the basis for their accessibility regulations and policies.

Why WCAG Matters

WCAG helps you create websites and applications that work for everyone, not just people who can see and use a mouse. It helps you reach a broader audience, avoid legal issues, and create more inclusive, professional applications.

It also helps you improve your SEO, create better user experiences for all users, and future-proof your designs as accessibility becomes increasingly important.

History and Versions

WCAG has evolved over time to address the changing nature of web technologies:

WCAG 1.0 (1999)

The initial release focused on HTML accessibility and introduced the concept of checkpoints.

WCAG 2.0 (2008)

A major revision that introduced the principles-based approach (POUR: Perceivable, Operable, Understandable, Robust) and established the three conformance levels (A, AA, AAA). WCAG 2.0 became an ISO standard (ISO/IEC 40500:2012) and is referenced in many legal requirements worldwide.

WCAG 2.1 (2018)

An extension of WCAG 2.0 that added 17 new success criteria focused on mobile accessibility, people with low vision, and people with cognitive and learning disabilities.

WCAG 2.2 (2023)

The newest version of WCAG, which adds 9 additional success criteria to address accessibility gaps, particularly for people with cognitive disabilities, low vision, and mobile device users.

WCAG 3.0 (In Development)

Currently under development with the working name "Silver," WCAG 3.0 aims to introduce a more flexible approach to accessibility measurement and a wider scope that includes more technologies and user needs.

Core Principles (POUR)

WCAG is organized around four fundamental principles, often referred to by the acronym "POUR":

1. Perceivable

Information and user interface components must be presentable to users in ways they can perceive.

Key concepts include text alternatives for non-text content, captions and alternatives for multimedia, content that can be presented in different ways, and content that is easier to see and hear.

2. Operable

User interface components and navigation must be operable by all users.

Key concepts include full keyboard accessibility, sufficient time to read and use content, avoidance of content that could cause seizures, navigable content with multiple ways to find pages, and input modalities beyond keyboard.

3. Understandable

Information and the operation of the user interface must be understandable.

Key concepts include readable and predictable text, content that appears and operates in predictable ways, and input assistance to help users avoid and correct mistakes.

4. Robust

Content must be robust enough to be reliably interpreted by a wide variety of user agents, including assistive technologies.

Key concepts include compatibility with current and future user tools, properly formed markup, and accessible names and roles for custom elements.

Conformance Levels

WCAG defines three levels of conformance, representing increasing levels of accessibility:

Level A (Minimum)

The most basic level of accessibility. Sites that don't meet Level A criteria have significant barriers that prevent many people with disabilities from using them.

Example criteria include providing text alternatives for non-text content, not using color alone to convey information, making all functionality available from a keyboard, and avoiding content that flashes more than three times per second.

The target level for most websites and the level referenced in most laws and policies. Level AA addresses significant barriers while being reasonably achievable for most websites.

Example criteria include providing captions for all live audio content, ensuring sufficient color contrast (4.5:1 for normal text), allowing text to be resized up to 200% without loss of content or function, providing multiple ways to find pages, and consistent navigation and identification.

Level AAA (Enhanced)

The highest level of accessibility, which addresses more subtle barriers. Level AAA may not be achievable for all types of content and is typically targeted for websites serving specialized audiences.

Example criteria include providing sign language interpretation for all prerecorded audio, higher contrast ratios (7:1 for normal text), no time limits on activities, context-sensitive help for more complex functionality, and providing a mechanism to identify pronunciation of words.

Success Criteria Structure

Each WCAG success criterion follows a consistent structure:

Number and level (e.g., "1.1.1 Non-text Content (Level A)")

Title is a brief description of what the criterion addresses.

Intent is an explanation of why the criterion is important.

Success criterion text is the actual requirement that must be met.

Sufficient techniques are methods that are sufficient to meet the criterion.

Advisory techniques are additional methods that enhance accessibility.

Failures are common mistakes that cause accessibility barriers.

Key Success Criteria Examples

Perceivable

1.1.1 Non-text Content (Level A)

All non-text content (images, icons, etc.) must have a text alternative that serves the equivalent purpose.

1.3.1 Info and Relationships (Level A)

Information, structure, and relationships conveyed through presentation must be programmatically determined or available in text.

1.4.3 Contrast (Minimum) (Level AA)

Text and images of text must have a contrast ratio of at least 4.5:1 (3:1 for large text).

Operable

2.1.1 Keyboard (Level A)

All functionality must be operable through a keyboard interface.

The purpose of each link can be determined from the link text alone or from the link text together with its programmatically determined context.

Understandable

3.2.2 On Input (Level A)

Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component.

3.3.1 Error Identification (Level A)

If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text.

Robust

4.1.2 Name, Role, Value (Level A)

For all user interface components, the name and role can be programmatically determined; states, properties, and values can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies.

Testing and Evaluation

Automated Testing

Automated tools can check for many WCAG violations, but they typically can only identify about 20-30% of potential issues. Popular tools include Axe DevTools, Lighthouse, WAVE, IBM Equal Access Accessibility Checker, and SiteImprove Accessibility Checker.

Manual Testing

Comprehensive WCAG evaluation requires manual testing by people familiar with assistive technologies (screen readers, etc.), keyboard-only navigation techniques, WCAG requirements and interpretations, and various disability scenarios.

User Testing

The most valuable feedback comes from user testing with people who have disabilities, as they can identify real-world barriers that might be missed in technical evaluations.

Common Implementation Approaches

Technical Approach

Audit and planning involves identifying current compliance level and creating a remediation plan.

Fix critical barriers involves addressing Level A issues first.

Progressive enhancement involves incrementally improving to Level AA.

Documentation involves maintaining an accessibility statement and policy.

Continuous integration involves including accessibility checks in development processes.

Organizational Approach

Policy development involves creating organizational accessibility standards.

Training involves educating teams about WCAG requirements.

Defined roles involves assigning responsibility for accessibility to specific team members.

Regular testing involves scheduling regular WCAG compliance checks.

Procurement standards involve requiring WCAG compliance from vendors and third parties.

WCAG has been adopted or referenced in accessibility laws and regulations worldwide:

United States includes Americans with Disabilities Act (ADA) and Section 508 of the Rehabilitation Act.

European Union includes European Accessibility Act and EN 301 549.

United Kingdom includes Equality Act 2010.

Canada includes Accessibility for Ontarians with Disabilities Act (AODA).

Australia includes Disability Discrimination Act.

Many other countries have various accessibility regulations.

Most jurisdictions reference WCAG 2.0 or 2.1 Level AA as the required standard for compliance.

Benefits Beyond Accessibility

Implementing WCAG provides benefits beyond accessibility:

Improved SEO occurs because many WCAG requirements align with search engine optimization best practices.

Mobile optimization happens because accessible sites often perform better on mobile devices.

Usability for all occurs because accessibility improvements benefit all users, not just those with disabilities.

Future-proofing happens because accessible websites are more adaptable to new technologies and devices.

Market expansion occurs because accessible websites can reach the approximately 15% of the global population with disabilities.

Getting Started

If you want to improve your WCAG compliance, begin with these fundamentals:

Start by understanding the four core principles: Perceivable, Operable, Understandable, and Robust.

Focus on achieving Level AA compliance, which is the target for most websites.

Use automated testing tools to identify basic issues, but remember they only catch about 20-30% of problems.

Test with real users who have disabilities to identify real-world barriers.

Include accessibility checks in your development process from the beginning.

Remember that WCAG is about creating websites that work for everyone, not just people who can see and use a mouse. The key is to focus on the four core principles and implement them systematically. When done well, WCAG compliance becomes a competitive advantage, enabling you to reach a broader audience and create better experiences for all users.

Related Terms