WCAG 2.0

What are the Web Content Accessibility Guidelines?

The Web Content Accessibility Guidelines, often abbreviated to WCAG, are a series of guidelines for improving web accessibility. Produced by the World Wide Web Consortium (W3C), the WCAG are the best means of making your website useful to all of your users.

Although they are not an all-inclusive list of issues facing web users with disabilities, they are internationally recognised and adopted standards. The guidelines explain how to solve many of the problems that your users with disabilities face.


Web Content Accessibility Guidelines 1.0

The W3C’s first incarnation of WCAG in 1999 was a huge leap in web accessibility, bringing together years of useful work by developers from across the world. The Web Content Accessibility Guidelines 1.0 had 14 guidelines and divided them into 3 priority levels:

    Priority 1 – the most basic level of web accessibility

    Priority 2 – addressed the biggest barriers for users with disabilities

    Priority 3 – significant improvements to web accessibility


Web Content Accessibility Guidelines 2.0

The current set of guidelines has been in force since 2008. The guidelines are more technologically neutral than WCAG 1.0, allowing them to stay useful for longer.

By designing WCAG 2.0 around principles and not technology, the W3C created an ethical statement as well as useful guidance.

The principles of WCAG 2.0 are:

    * Perceivable

    * Operable

    * Understandable

    * Robust

The beauty of a principled approach like POUR is the emphasis on understanding your users. Learning all the guidelines isn’t good enough if you don’t know why they exist.


The principle of a website being perceivable is all about the senses people use when browsing the web. Some of your users may have difficulties with one or more of their senses, making them reliant on assistive technology to browse your website.

The three main senses that the guidelines can help with are sight, sound and touch. With WCAG 2.0, you can make sure that users can perceive all the information on your website.


The principle of a website being operable is about the actions people take when browsing. This covers the different ways in which your users browse the web. Some of them may have motor difficulties, which means they use their keyboard to navigate and some users who have sight impairments often prefer to use a keyboard rather than a mouse too.

The main issues for making your website operable are, ensuring good keyboard-only navigation, avoiding setting time limits for your users and helping them out if they make errors on forms.


Making a website understandable is a different kind of task to the first two principles. A perceivable and operable website means nothing if your users can’t understand it.

Your website must use clear terms, have simple instructions and explain complex issues. You must also make your website function in a way that your users understand, by avoiding unusual, unexpected or inconsistent functions.


A robust website is one that third-party technology (like web browsers and screen readers) can rely on. Your website must meet recognised standards, such as using clean HTML and CSS. This minimises the risk of your users relying on technology that cannot correctly process your website.

WCAG 2.0 levels

The Web Content Accessibility Guidelines 2.0 are organised into three levels of conformance:

    Level A – the most basic web accessibility features

    Level AA – deals with the biggest and most common barriers for disabled users

    Level AAA – the highest (and most complex) level of web accessibility

For most websites, Level AA plus some Level AAA is the best target. That’s because some of the highest level guidelines simply can’t be applied to all websites. However, one of the problems with the three-tier structure is that if people know they can’t attain AAA, they won’t even look through the guidelines to see where they can improve accessibility. With all of your projects, you should comply with all the guidelines you can, whether you want Level AAA or not.

Starting with Level A is a great way to make progress and begin helping out your users. Level AA is the standard many governments are using as a benchmark as this level targets the most common and most problematic issues for web users.

Web Content Accessibility Guidelines 2.1

WCAG 2.0 was published on 11 December 2008. WCAG 2.1 was published on 5 June 2018.

All requirements (“success criteria”) from 2.0 are included in 2.1. The 2.0 success criteria are exactly the same (verbatim, word-for-word) in 2.1.

There are additional success criteria in 2.1 that are not in 2.0. They are introduced in What’s New in WCAG 2.1.

Content that conforms to WCAG 2.1 also conforms to WCAG 2.0. (This is often called “backwards compatible”.) A website that meets WCAG 2.1 should meet the requirements of policies that reference WCAG 2.0.

To put it another way: If you want to meet both WCAG 2.0 and WCAG 2.1, you can use the 2.1 resources and you don’t need to bother looking at 2.0.

WCAG 2.0 and WCAG 2.1 are both existing standards. WCAG 2.1 does not deprecate or supersede WCAG 2.0. W3C encourages you to use the most recent version of WCAG when developing or updating content or accessibility policies.

Frequently asked questions about WCAG 2.1

Q. Is WCAG 2.1 backward compatible with WCAG 2.0?

A. Yes! WCAG 2.0 is still a valid and very useful standard. WCAG 2.1 works in concert with WCAG 2.0.

Q. Does WCAG 2.1 continue to use the WCAG 2.0 the A, AA, and AAA conformance levels?

A. Yes. WCAG 2.1 uses the same A/AA/AAA conformance levels

Q. What are the main areas of focus for WCAG 2.1?

A. The three biggest gaps in WCAG 2.0 are related to:

Mobile technology – mobile phones were not very smart back in 2008, and this platform evolves rapidly. It is no surprise that there are accessibility needs related to mobile that must be addressed. The Mobile Accessibility Task Force (MATF)was created to address accessibility challenges for mobile.

Low vision – accessibility requirements for people with low vision have been well documented for years. The time has come to remove barriers for the estimated 246 million people worldwide who have low vision. The Low Vision Task Force (LVTF) was created to address accessibility issues specific to low vision.

Cognitive disabilities – the area that I think will have the most innovation and profound impact on universal design is cognitive. As we find solutions to the challenges documented in Cognitive Accessibility User Research and the Cognitive Accessibility Roadmap and Gap Analysis I predict we will discover that we have improved the web for everyone. The Cognitive and Learning Disabilities Accessibility Task Force (COGA) was created to address accessibility issues specific to cognitive disabilities.


WCAG 2.0 W3C Recommendation:

WCAG 2.1 W3C Recommendation:

WCAG 2.1 checklist by WebAIM: