1.2.2 About WCAG 2.0

The World Wide Web Consortium (W3C) has developed and maintains a widely accepted set of technical guidelines for accessible websites. The consortium is an international community whose full-time staff, member organizations, and the public work together to develop web standards.

The Web Content Accessibility Guidelines are typically referred to by their acronym WCAG (pronounced "wick-ag"). The technical requirements described and referenced in this guide are based on WCAG 2.0 — the most current version of the guidelines at the time of writing.

WGAC 2.0 is a comprehensive set of documents, specifications and techniques dealing with all aspects of accessibility for websites and web content. It is not the intent of this guide to identify and explain all of the technical requirements. That information is dealt with in the guidelines. However, this guide will help you understand the intent and organization of WCAG 2.0 as well as how to use the WCAG resources for your own web development projects.

WCAG 2.0 is structured around four major questions related to web content.

A closeup picture of a computer keyboard with a blue key showing the universal symbol for accessiblity.
  1. Is it perceivable?
  2. Is it operable?
  3. Is it understandable?
  4. Is it robust?

These questions inform the four, overarching principles established in WCAG 2.0 — perceivable, operable, understandable and robust. Each principle is related to one or more guidelines which, if followed, will lead to more accessible websites and web content.

Principle 1: Perceivable - Information and user interface components must be presentable to users in ways they can perceive.

Guideline 1.1 Text Alternatives: Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.

Guideline 1.2 Time-based Media: Provide alternatives for time-based media.

Guideline 1.3 Adaptable: Create content that can be presented in different ways (for example simpler layout) without losing information or structure.

Guideline 1.4 Distinguishable: Make it easier for users to see and hear content including separating foreground from background.

Principle 2: Operable - User interface components and navigation must be operable.

Guideline 2.1 Keyboard Accessible: Make all functionality available from a keyboard.

Guideline 2.2 Enough Time: Provide users enough time to read and use content.

Guideline 2.3 Seizures: Do not design content in a way that is known to cause seizures.

Guideline 2.4 Navigable: Provide ways to help users navigate, find content, and determine where they are.

Principle 3: Understandable - Information and the operation of user interface must be understandable.

Guideline 3.1 Readable: Make text content readable and understandable.

Guideline 3.2 Predictable: Make Web pages appear and operate in predictable ways.

Guideline 3.3 Input Assistance: Help users avoid and correct mistakes.

Principle 4: Robust - Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.

Guideline 4.1 Compatible: Maximize compatibility with current and future user agents, including assistive technologies.


A laptop computer showing a website, with images of other websites on either side of the screen, implying the testing of the accessibility level of websites.

Every guideline has criteria for success that can be tested. Web developers and others use these criteria when testing for the requirements or conformity necessary to meet design specifications, purchasing regulations and contract agreements.

For example, the guidelines require developers to make websites and web content distinguishable. One testable success criterion for this guideline is that colour can't be used as the sole method of conveying content or differentiation. In other words, you can't say fill out the fields marked in red.

Finally, for each guideline and success criteria the WCAG links to "Sufficient and Advisory Techniques" which provide instructions on how to code for accessibility.

The WCAG 2.0 principles apply to more than the HTML that may form the template of a web page. The principles apply to any other format, application or technology you use to create a page or embed content in a page. This means that if you embed a multimedia player in a page then that player, its controls and output must be accessible to the same level of compliance you claim for your overall page.

Please visit the full Web Content Accessibility Guidelines (WCAG) 2.0 [ http://www.w3.org/WAI/WCAG20/quickref/ ]