WCAG 2.0: The International Standard for Web Accessibility and Inclusive Design

August 31, 2018 BY SOFIA ENAMORADO
Updated: July 13, 2021

download: wcag 2.0 and 2.1 white paper

Aside from state and federal web accessibility laws, the most widely adopted and comprehensive technical standards have emerged not from a law, but from the W3C’s Web Content Accessibility Guidelines (WCAG).

This standard is the most detailed, up-to-date guideline for creating accessible web content. Although in the United States it is not yet backed by law, it has been voluntarily accepted and employed by numerous American educational institutions. It has also been referenced by laws in 21 countries and the EU.

Read on to learn why these guidelines are rapidly emerging as the international standard of web accessibility.

What is the World Wide Web Consortium (W3C)?

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WCAG was developed by the World Wide Web Consortium (W3C). Although their focus is not solely on accessibility, the W3C is widely regarded as the highest authority in web accessibility goals and universal design.

The consortium provides an online web development resource center that includes sample code implementations to demonstrate and encourage the use of standards, as well as prototypes and sample applications to illustrate new technology.

What are Web Content Accessibility Guidelines?

The Web Content Accessibility Guidelines, are a set of standards making digital content accessible for all users, specifically, users with disabilities.

W3C has released three versions: version 1.0, 2.0, and 2.1.

WCAG is a set of guidelines for making content accessible for all users, including those with disabilities.

The WCAG standard:

  • Outlines best practices for making web content universally perceivable, operable, understandable, and robust.
  • Defines criteria for successful inclusive web design, with ascending levels of compliance (levels A, AA, and AAA).
  • Is composed and reviewed by a global community of digital experts.
  • Connects the world through common information technology and user experience standards.

What is the difference between Version 1.0, 2.0, and 2.1?

A preliminary version of WCAG was released in January 1995, followed by WCAG 1.0 in 1999. WCAG 2.0 was released in December 2008 and WCAG 2.1 was released in June 2018.

Version 1.0 differs from versions 2.0 and 2.1 in the way they organize accessibility guidelines. WCAG 1.0 uses priority levels, whereas the WCAG 2.0 and 2.1 are oriented around four universal design principals.

Most accessibility laws around the world reference WCAG 2.0.

WCAG 1.0

ball and triangle

This version uses guidelines to address accessible design. These guidelines address two themes: ensuring graceful transformation, and making content understandable and navigable.

Each guideline under WCAG 1.0 has a checkpoint, which are priority 1, 2, or 3.

  • Priority 1: address criteria a web developer “must satisfy”
  • Priority 2: lists criteria a web developer “should satisfy”
  • Priority 3: supplies optional checkpoints a web developer “may address”

Because WCAG 1.0 was published in 1999, it primarily addresses HTML web pages, since that was the majority of web content at the time. It did not account for advances in technology, new software, and advanced applications of digital content.

As of 2019, WCAG 1.0 will be superseded, meaning it will be overwritten by WCAG 2.1.

WCAG 2.0


WCAG 2.0’s essential design concepts are labeled perceivable, operable, understandable and robust.

Designers and developers are asked to meet all four of these principals for disabled users, and then select a degree of compliance (Level A, AA, or AAA).

The four design principals are defined as follows:

  • Perceivable: Information and user interface components must be presentable to users in ways they can perceive. This means that users must be able to perceive the all relevant information in your content.
  • Operable: User interface components and navigation must be operable. This means that users must be able to operate the interface successfully.
  • Understandable: Information and the operation of user interface must be understandable. This means that users must be able to understand the information as well as the operation of the user interface.
  • Robust: Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies. Content must be accessible to all users, keeping up with advances in technology, such as mobile technology.

WCAG 2.1

dots in a line

This is the newest release from W3C. WCAG 2.1 is an extension of WCAG 2.0. It includes 17 new standards that benefit individuals with cognitive or learning disabilities, users with low vision, and all mobile users.

WCAG 2.1 is backward compatible with WCAG 2.0. It follows the same structure, principles, and compliance levels as WCAG 2.0.

WCAG 2.2

On February 27, 2020, the W3C released its first public working draft of WCAG 2.2. Read more about WCAG 2.2 here.

WCAG 2.0 & 2.1 Compliance: Level A vs. AA vs. AAA

Most accessibility laws require compliance with Level A and Level AA.

WCAG 2.0 and 2.1 outline three levels of compliance. Level A is the highest priority and usually the easiest to achieve. Level AA is more comprehensive. Level AAA is the strictest, most comprehensive accessible design.

For example, compare the success criteria for accessible navigation.

  • Level A: (2.4.2) Web pages have titles that describe topic or purpose.
  • Level AA(2.4.5) More than one way is available to locate a Web page within a set of Web pages except where the Web Page is the result of, or a step in, a process.
  • Level AAA (2.4.10) Section headings are used to organize the content.

These all seem to be fairly common sense best practices for universal web design, and most web designers should be able to achieve Level AAA compliance for this.

Other facets of WCAG compliance levels are far more involved, whether they require more resources, coordination, or funds to meet. For instance, compare the WCAG compliance levels for accessible video and time-synced media:

  • Level A: (1.2.2) Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such.
  • Level AA: (1.2.4) In addition to Level A compliance, captions are provided for all live audio content in synchronized media.
  • Level AAA: (1.2.6) In addition to Levels A and AA compliance, sign language interpretation is provided for all prerecorded audio content in synchronized media.

WCAG 2.0 Level AA: a Happy Medium

dots and squiggles

WCAG documentation implies that meeting success criteria should not adversely impact the user experience. Since closed captions can be toggled on and off, they do not compromise the visual presentation. On the other hand, adding sign language interpretation might be more likely to impact the interface given the limitations of current video player technology.

To this end, the W3C is first to recognize that most organizations simply won’t be able to achieve Level AAA success, at least not right away.

In note 2 of the WCAG 2.0, W3C states:

“It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.”

It is recommended, however, that web designers meet at least WCAG 2.0 Level A and aim for Level AA compliance.

Webmasters should heed this recommendation, since American disability law Section 508’s ICT refresh references WCAG 2.0 Level AA as the standard to shoot for. WCAG 2.0 Level AA is already best practice for government websites in the UK, Canada, New Zealand, and Australia.

71% of people with disabilities leave a website immediately if it is not accessible.

Web Content Accessibility Guidelines & Video Accessibility

Accessible video includes captions, transcripts, audio description and an accessible media player that supports these features.

Video accessibility requirements are written in WCAG and can be found under 1.2 Time-Based Media.

Both captions and audio description are Level A requirements for pre-recorded video.

Level A

  • 1.2.1 Audio-only & Video-only (Pre-recorded)
  • 1.2.2 Captions (Pre-recorded)
  • 1.2.3 Audio description or media alternative (Pre-recorded)

Level AA

  • 1.2.4 Captions (Live)
  • 1.2.5 Audio Description (Pre-recorded)

Level AAA

  • 1.2.6 Sign Language (Pre-recorded)
  • 1.2.7 Extended Audio description (Pre-recorded)
  • 1.2.8 Media Alternative (Pre-recorded)
  • 1.2.9 Audio Only (Live)

WCAG 2.0 Standard at a Glance

WCAG 2.0 has 4 principles with 12 guidelines scattered across each principle. Each guideline also has a success criteria assigned to it.


Text alternatives


Non-text content must have text alternatives.


The purpose is to allow Non-text content to be converted into other forms people need such as braille, large print, speech, symbols, or simpler language.

Who does this benefit?

This guideline benefits a range of people as it allows them to consume content in a way that best meets their needs.


Video Alternatives


read: wcag compliant videos

Content creators must provide alternatives to video and audio.


Video content is not accessible to many people. Having an alternative allows those people to also enjoy your content.

Who does this benefit?

This standard benefits people who are deaf, hard of hearing, blind, and low vision. It also provides a better user experience for everyone, as solutions like captioning help improve engagement and comprehension of content.




Web developers should create content that can be presented in different ways without losing structure or information.


This standard ensures content can be converted into other forms people need through software.

Who does this benefit?

This allows people to access content in different ways – visually, audibly, tactilely etc.




squiggle lines

Content should be easy for users to see, read, and hear. Visually, background should have enough color contrast. Audibly, foreground sounds should be louder than background sounds.


Information should be easy for the user to perceive.

Who does this benefit?

This benefits users with both hearing and visual disabilities as it gives them more clarity over the information being presented.


Keyboard Accessibility


All website functions should be accessible through a keyboard alone.


Keyboard accessibility is the most flexible and universally supported method for navigation.

Who does this benefit?

Keyboard accessibility benefits many users. It allows users with motor disabilities to access a website, as well as blind users who use a keyboard to navigate. It also benefits people with tremors who have little muscle control, and people who have limited use of their hands, or have no hands due to a birth defect, accident, or amputation.




Users should be provided with enough time to read and use the content.


Some users may take longer to complete forms or other commands. This guideline ensures that individuals are given enough time to complete tasks at their won individual response times.

Who does this benefit?

People with physical disabilities who may need more time to react; people with low vision who need time to locate things on the screen; people who are blind and using screen readers and may need more time to understand the website layout; people with cognitive or language limitations; people with reading disabilities, cognitive limitations, and learning disabilities who may need more time to read or comprehend information.

30% of working professionals have a disability


Seizure Safety


Content should not be designed in a way that could trigger a seizure.


Flashing visual content can trigger seizures. Most people don’t know they have a seizure disorder until it happens.

Who does this benefit?

This guideline protects people who have photosensitive epilepsy.




Web developers should provide multiple, intuitive ways for users to navigate content.


This guideline serves to help users find the content they need and track their location.

Who does this benefit?

This guideline benefits users who use assistive technologies to navigate a page. With proper web design, they can easily locate information.




ball and triangle

Content should be easy to read and understand, both visually and cognitively.


This guideline ensures text can be read by users and assistive technologies.

Who does this benefit?

This guideline benefits many different types of users. Some users have a harder time recognizing words or inferring the meaning of a word. In addition, for people using assistive technologies, a proper definition of the language is imperative for its functionality.




Pages should appear and operate in predictable ways.


This guideline ensures uniformity for how web pages behave and function throughout the web.

Who does this benefit?

This guideline makes it easier for people using screen readers, people who use screen magnifiers, and people with cognitive limitations who may be confused if components of a website appear in different locations on different pages. This also helps users with limited use of their hands to easily determine where they want to go with few keystrokes.


Input Assistance


A mechanism should be in place to help users avoid making mistakes, or to help users make corrections easily.


This helps to reduce the number of serious or irreversible errors and alerts users that an error has been made so they can correct it.

Who does this benefit?

For certain people, it can be hard to correct or detect errors. This ensures that they are inputting correct information.




Web developers should maximize compatibility across devices and make sure content is compatible with assistive technologies.


To support compatibility with current and future user agents like assistive devices, desktops, tablets, mobiles, etc.

Who does this benefit?

This ensures web content is accessible for all users, on whichever device the user chooses to use.

What to Know About WCAG 2.1

WCAG 2.1 is an extension of version 2.0. It’s backwards compatible, which means that content that conforms to WCAG 2.1 also conforms to WCAG 2.0.

Do I Have to Conform to 2.1?

read: what you should know about wcag 2.1

Most laws around the world reference WCAG 1.0 and WCAG 2.0. As an organization, you should be meeting the standards under the law.

Some laws have clauses that say you need to comply with the latest version of of the Web Content Accessibility Guidelines. In this case, you would need to meet WCAG 2.1 standards.

W3C does suggest designing websites under WCAG 2.1, as these laws are more inclusive and mobile friendly.

What Changed Under 2.1?

Version 2.1 includes 17 new standards that place a higher emphasis on functionality and mobile optimization.

Some highlights include:

  • Mobile accessibility guidelines
  • Limits on interruptions, like pop-ups
  • Improves navigation technology to reduce clicking on incorrect links or button
  • New standards benefit low vision users; these include 400% zoom, 3:1 contrast level, and better labeling

For a full outline of the new standards under WCAG 2.1, you can refer to this article, “What You Should Know About WCAG 2.1”.

WCAG and Section 508

Section 508 of the Rehabilitation Act is the only US federal law that includes a technical standard on web accessibility. It preceded the creation of WCAG standards, which are substantially more complete and better adapted to modern web technology.

Section 508 was refreshed by the U.S. Access Board. As of January 18, 2018, Section 508 now requires compliance with WCAG 2.0 Level A and AA success criteria.

Section 508 applies to:

  • Federal departments and agencies
  • State governments through “little 508s”
  • Organizations with institutional 508 requirements or grants that require compliance with Section 508

Many states have enacted “little 508s” and/or WCAG compliance.

map of america with states highlighted that have WCAG requierments. this includes alabama, alaska, arizona, california, colorado connecticut florida hawaii illinois indiana iowa kansas kentucky louisina maine

Worldwide Web Accessibility Standards


While many disability laws lag behind in addressing digital access, WCAG 2.0 provides the most comprehensive web accessibility standard available today.

Many organizations use it as a guide for inclusive web design. Outside of the US, WCAG 2.0 has been directly referenced or adopted by 20 countries and the European Union.

The following table shows government accessibility standards and relevant legislation




Country Standard Legislation Requirements
Argentina WCAG 1.0 Guide to Accessibility for Websites of the National Public Sector Public sector websites must meet WCAG 1.0.
Australia WCAG 2.0 AA Disability Discrimination Act All government websites should comply with WCAG 2.0 AA by the end of 2014.
Bolivia WCAG 2.0 AA Standard Guide for Websites Not mandatory, but recommended compliance with several WCAG 2.0 Level A and AA standards.
Brazil WCAG 2.0 AA Accessibility Model for Electronic Government Operations Standards are based off WCAG 2.0. Applies to government operations.
Canada WCAG 2.0 AA
SGQRI 008 (based on WCAG 2.0)
Human Rights Act 1977
Ontarians with Disabilities Act (AODA)
Quebec: Standards sur l’accessibilité du Web
WCAG 1.0 compliance is required for all government websites. The Jodhan vs. Attorney General of Canada ruling requires the Canadian government to meet WCAG 2.0, which was implemented in 2011.
Ontario: AODA is required for all new Ontario government websites and existing websites by January 2016.
Quebec: Custom made standard based on WCAG 2.0 with specifics covering websites, downloadable documents and multimedia.
Brazil WCAG 2.0 AA Accessibility Model for Electronic Government Operations Standards are based off WCAG 2.0. Applies to government operations.
Chile WCAG 1.0 & 2.0 Supreme Decree 100/206 of the Ministry of General Secretariat of the Presidency of the Republic of Chile Guidelines based on WCAG 1.0 & 2.0 apply to websites under the administrative state.
China WCAG 2.0 derivative Voluntary Web Accessibility Standards Agencies, ministries and other governmental entities must comply with a WCAG 2.0 derivative.
Columbia WCAG 2.0 AA The Institution of Colombia’s Technical Standards Government entities must comply with each level of WCAG 2.0 depending on the level of maturity.
Ecuador WCAG 2.0 AA Official Register No. 171 Any private or public organization that offers public services must meet WCAG 2.0 Level AA.
EU WCAG 1.0 AA European Parliament Resolution (2002) Required for all EU commission websites. Progress towards WCAG 2.0 is being made by the Mandate M 376 working group, which started work in 2006.
France RGAA 3 (based on WCAG 2.0) Law No 2005-102, Article 47 Updated in April 2015 to include best practices for HTML5 and ARIA. Required for all French government websites and French public websites (public services, municipal sites, public research, etc).
Germany BITV 2 (based on WCAG 2.0) Federal Disabled Equalization Law BITV 2 was enacted in 2011, and is required for all government websites. It is based on WCAG 2.0.
Hong Kong WCAG 2.0 AA WCAG 2.0 AA is the standard for government websites.
India Guidelines for Indian Government Websites (based on WCAG 2.0 Level A) WCAG 2.0 Level A became the standard for Indian government websites in February 2009.
Ireland WCAG 2.0 AA The Disability Act 2005 Required for all government websites.
Israel WCAG 2.0 AA Equal Rights of Persons with Disabilities Act Agencies, ministries and other governmental entities must comply with a WCAG 2.0 derivative.
Italy Technical Rules of Law 4/2004 (based on WCAG 1.0 AA) Law No. 4/2004 Required for all government websites.
Japan JIS X 8341 (based on WCAG 2.0) Required for all local and central government websites. Commercial websites are also encouraged to use it.
Netherlands WCAG 2.0 AA Government websites must comply with the government web guidelines. There are no requirements for non-government websites.
New Zealand New Zealand Government Web Standards 2.0 (WCAG 2.0 AA) Human Rights Amendment Act 2001 Required for all government web sites.
Norway WCAG 2.0 Level AA LOV 2008-06-20 nr 42 Requires all websites to be universally designed. Some exceptions to Level AA criteria are permitted regarding time-based media and social media.
Peru WCAG 1.0 Law No. 27050: General Law for People with Disabilities Web pages under the public institution of Peru’s National Information System must meet WCAG 1.0.
Republic of Korea WCAG 2.0 derivative Act on Prohibition of Discrimination Against people with Disabilities (Law No. 15272) Guidelines for public and private sector use a WCAG 2.0 derivative.
Spain UNE 139803:2012 (based on WCAG 2.0 Level AA) Law 34/2002, Law 51/2003 Required for all government websites. Not required for non-government websites.
United Kingdom WCAG 2.0 Level AA Equality Act 2010 Required for all UK government web sites. Other UK websites need to comply with the Equality Act and provide equal access, but this doesn’t specify technical standards.
Uruguay WCAG 2.0 AA Guide for Design and Implementation of Government Portals As a guideline, government portals must meet WCAG 2.0 Level AA and, when necessary, Level AAA.
USA WCAG 2.0 Level AA Section 508 of Rehabilitation Act US federal agencies’ websites must comply with Section 508 guidelines. Section 508 is undergoing an ICT refresh that “seeks to harmonize its requirements with various voluntary consensus standards, including the Web Accessibility Initiative’s Web Content Accessibility Guidelines (WCAG).”
Venezuela WCAG 1.0 & 2.0 Resolution 026 Recommends use of WCAG 1.0 and WCAG 2.0 standards as guidelines when building websites.


So much of our modern life takes place online. It is not fair to make the web inaccessible to some.

This sentiment rings true with technology leaders around the globe who herald WCAG 2.0 as the prevalent standard in web accessibility. For so many countries, WCAG is literally law. For the United States, it’s only a matter of time before the WCAG standard has legal backing.

Accessibility aside, WCAG creates clearer communication through standardization. As such, agencies, institutions, and businesses should apply WCAG 2.0 principles if they want to stay current in the digital age.

download the white paper: wcag 2.0 and 2.1 bringing accessibility into the 21st century

This post was originally published on November 25, 2013 by Shannon Murphy as “WCAG 2.0: Emerging Standard for Web Accessibility and Video Captions,” and has been updated.

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