The Web Content Accessibility Guidelines (WCAG) are the most important global standard for web accessibility from the Web Accessibility Initiative (WAI) when it comes to digital accessibility of websites and web applications. The WCAG provide structured guidance for designing accessible web content.

The WCAG define success criteria and WCAG requirements for digital accessibility. These new success criteria are important for ensuring the web accessibility and usability of digital content so that websites are accessible to everyone, especially people with disabilities and limitations.

This article explains exactly what the Web Content Accessibility Guidelines (WCAG) are and why they are important. What can companies do to implement the WCAG?

What are the WCAG?

The abbreviation WCAG stands for Web Content Accessibility Guidelines. It is a set of rules developed by the World Wide Web Consortium (W3C) working group on accessibility standards. The W3C is an international body that has been formulating recommendations for web standards since 1994.

The WCAG 2.1 guidelines serve to improve the accessibility of web content in order to better meet the needs of users with various disabilities.

The WCAG 2.1 guidelines are a further development of the WCAG 1.0 guidelines adopted in 1999. The WCAG 2.1 guidelines comply with ISO standard 40500. The European standard EN 301 549 for the implementation of the EAA also refers to the Web Content Accessibility Guidelines.

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International laws and guidelines for websites

Various laws, guidelines, and regulations govern the accessible design of websites for public authorities and private companies internationally. Examples include:

Structure of the Web Content Accessibility Guidelines (WCAG)

The first 75 pages of WCAG 2.1 clearly illustrate the diversity of requirements and criteria for digital accessibility and web accessibility.

Digital accessibility and web accessibility according to the W3C Accessibility Guidelines is to be achieved through a specified structure for websites and apps that enables all people to access and use them equally.

The most important types of disabilities are distinguished here:

  • Visual impairment and blindness

  • Cognitive and learning disabilities

  • Motor disabilities

  • Hearing impairment and deafness

  • Photosensitivity

  • Multiple, specific disabilities

The Web Content Accessibility Guidelines are an international standard for accessible web development and are available in several translations. The WCAG are basically structured in four levels: principles, guidelines, success criteria, and techniques.

Four Principles of Accessibility According to the Web Content Accessibility Guidelines

The WCAG are based on four fundamental web accessibility principles, which are summarized under the term “POUR.”

  1. Perceivable: All web content must be designed so that it can be accessed by various perception and input aids (e.g., screen readers, Braille displays, enlarged text).

  2. Operable: Users must be able to operate all functions of a website or application using different input methods (keyboard, voice control, mouse, etc.).

  3. Understandable: Web content and operating concepts should be easy to understand. This includes, for example, clear language, consistency, and predictability in navigation. Avoid unusual words or idioms that may confuse users with cognitive disabilities.

  4. Robust: A website must be compatible with different user agents, such as browsers or assistive technologies.

WCAG-Compliant CAPTCHAs for Best Web Accessibility

Accessibility principles are particularly important for all interactive user interfaces components such as e-commerce shops, such as logins, registrations, forms, or checkouts. On the one hand, these interfaces must be protected against bot attacks with CAPTCHAs.

On the other hand, the CAPTCHAs used must be checked for accessibility. The best-known provider of accessible CAPTCHAs is Friendly Captcha. It meets all four basic accessibility principles of the WCAG.

Success Criteria for WCAG Web Accessibility

Each individual guideline consists of defined success criteria. This allows the Web Content Accessibility Guidelines to be tested for concrete implementation using tests such as the WCAG Checker from Friendly Captcha. Test your website now for accessibility and WCAG conformance free of charge.

The following versions of the guidelines for accessible web content are distinguished:

  • WCAG 2.0 (published in 2008): The original version on which all further updates are based.

  • WCAG 2.1 (published in 2018): Includes improvements for mobile devices and touch navigation and adds criteria primarily for mobile accessibility and users with visual and cognitive impairments.

  • WCAG 2.2 (2024): Contains additional guidelines, in particular for improving accessibility and interactivity and clarity of web content.

All versions are backwards compatible. This means that companies that comply with WCAG 2.2 automatically conform to WCAG 2.0 and WCAG 2.1.

The success criteria for WCAG web accessibility also define the four levels of compliance (A, AA, and AAA). WCAG Level A is the lowest level, but has the highest priority for implementation.

WCAG conformance level AAA corresponds to the highest level with the lowest priority. Most legal frameworks require at least Level AA success criteria to be fulfilled.

The WCAG are divided into three compliance levels:

  • Level A success criteria: The lowest level, Level A, of the Web Content Accessibility Guidelines contains basic requirements that are often relatively easy to implement (e.g., alt text for images, keyboard operation).

  • Level AA success criteria: Level AA builds on Level A and includes additional important points (e.g., specific contrast ratios, accessibility of controls). Level AA is often recommended as the minimum standard for many organizations.

  • Level AAA success criteria: The highest level, Level AA, has the most stringent requirements (e.g., simplest language, comprehensive audio descriptions). Level AAA is often only realistic for selected content. Level AAA conformance is the most comprehensive but least legally required.

Techniques for WCAG Conformance and Web Accessibility

Specific techniques for implementation are documented for each WCAG guideline and the WCAG success criteria. Each success criterion is designed to be a testable success criterion for conformance checking.

These are differentiated between sufficient techniques to meet an accessibility success criterion and recommended techniques that offer more than the minimum standard. Accessibility can only be achieved if the compliance conditions are met.

What Are WCAG Requirements for Web Accessibility?

If you want to design your web content to be accessible in accordance with the Web Content Accessibility Guidelines or WCAG, you should keep a few key points in mind:

  • Color contrast: a sufficient contrast ratio between text and background; ensure sufficient contrast between text and background colors

  • Alt text for images: All graphics and photos should have alternative text (alt text) so that screen reader users can understand web content.

  • Clear page structure: When opening a new page or web page follow a clear heading hierarchy (H1, H2, H3, etc.), format lists correctly, choose meaningful link texts (“Learn more” is less clear than “Learn more about accessible web design”).

  • Keyboard operability: All web page functions should be usable without a mouse. It is important that visible focus indicators are present and that users can see where they are currently located.

  • Simple language & comprehensibility: Complicated texts make understanding difficult. Short sentences, clear technical terms, and explanations of abbreviations where necessary are helpful measures.

  • Timeouts or moving content: Content that moves, flashes, or plays automatically should be pausable or stoppable. This applies, for example, to image sliders, videos, and advertising banners.

  • Media alternative: All content, tools and media must provide transcripts for audio files and descriptions for video-only content.

Web Content Accessibility Guidelines as the Key to Digital Accessibility

The Web Content Accessibility Guidelines form the foundation of modern web and app development with a focus on accessibility. They are internationally recognized and often required by law.

A WCAG-compliant website:

  • Expands your target audience because more people can access your content.

  • Enhances the user experience because clear structures and good readability benefit everyone.

  • Minimizes legal risks by ensuring compliance with legal requirements.

Start working on WCAG implementation and comply with the European Accessibility Act (EAA) by June 28, 2025. Test your website for accessibility for free with the WCAG Checker from Friendly Captcha.

FAQ

WCAG is an abbreviation that stands for Web Content Accessibility Guidelines. As accessibility guidelines from the World Wide Web Consortium (W3C), the WCAG provide specific instructions for accessible websites, online shops, and apps. They define accessibility requirements so that websites and apps are accessible to everyone, especially people with disabilities.

The WCAG cover various aspects such as perception, usability, comprehensibility, and robustness. If you want to check your website for WCAG compliance, you can do so with the WCAG Checker from Friendly Captcha.

Basically, the Web Content Accessibility Guidelines (WCAG) are a recommendation for anyone who wants to provide accessible web content and accessible web pages. In many countries, accessibility is even required by law for government institutions and public facilities. This applies, for example, to:
  • Public authorities and agencies (ministries, municipalities, universities, libraries, etc.)
  • Companies that are subject to certain laws (e.g., the European Accessibility Act in the EU or Section 508 in the US)
In addition, many companies voluntarily emphasize WCAG compliance in order to make their offerings accessible to everyone and to prevent potential legal risks.
Yes, Friendly Captcha is a WCAG-compliant CAPTCHA. Friendly Captcha is based on invisible background challenges and does not require any manual interaction on the part of the user. Friendly Captcha is not only WCAG-compliant and therefore completely accessible, but also complies with international data protection laws such as the GDPR and CCPA.

The WCAG are continuously developed by the World Wide Web Consortium (W3C). The versions build on each other:

  • WCAG 1.0 (1999): First guidelines for accessible web content
  • WCAG 2.0 (2008): Basic accessibility standards for web content (A, AA, and AAA).
  • WCAG 2.1 (2018): Contains 17 new success criteria, particularly for mobile use, people with visual impairments, and users with cognitive limitations.
  • WCAG 2.2 (2024): Adds further criteria to further reduce accessibility barriers and accessibility issues on the web (e.g., focus highlighting, drag-and-drop functionality).

The older standards (WCAG 1.0 and WCAG 2.0) still exist – newer versions supplement or tighten the requirements without violating existing WCAG guidelines.

The deadlines by which your web page must be accessible vary depending on the country and legal jurisdiction. In the European Union, for example, public authorities have been required to make their websites and mobile applications accessible since September 2020.
In addition, the European Accessibility Act (EAA) will come into force on June 28, 2025, which will also require many private companies (e.g., e-commerce, online banks) to make their web content accessible.

There are several approaches to checking the accessibility of a web page:

  1. Manual tests:
    • Use simple checklists (e.g., check contrast, test keyboard navigation, check alt texts)
    • Test with screen reader software or voice control
  2. Expert opinions:
    • Agencies or accessibility consultants offer detailed analyses and recommendations for action for a fee.
  3. User feedback:
    • Have people with disabilities test your website to uncover real barriers to use and accessibility issues.
  4. Automated tools:
    • WCAG Checker from Friendly Captcha provides a quick and free initial overview of accessibility issues.

For companies, checking their website with an automated tool such as Friendly Captcha’s WCAG Checker is a good start toward greater accessibility. In addition, manual testing can help achieve WCAG compliance.

The cost of designing an accessible web page can vary greatly. The following factors influence the financial outlay:

  • Scope and complexity of the website (e.g., number of pages, interactions, applications).
  • Current accessibility status: Does everything need to be developed from scratch, or are only partial adjustments necessary?
  • Internal or external expertise: Does the team already have accessibility know-how, or is an external agency/consultant needed?
  • Technical platform: Which content management system is used and are there any existing accessibility plugins?

It is often worthwhile to plan accessibility aspects early in the project. Subsequent corrections can consume more time and budget than if accessibility is taken into account from the outset.

With cybersecurity threats on the rise, organizations need to protect all areas of their business. This includes defending their websites and web applications from bots, spam, and abuse. In particular, web interactions such as logins, registrations, and online forms are increasingly under attack.

To secure web interactions in a user-friendly, fully accessible and privacy compliant way, Friendly Captcha offers a secure and invisible alternative to traditional captchas. It is used successfully by large corporations, governments and startups worldwide.

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