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This page is an archive. Please see the updated page for WCAG 2.2 for the most complete information.

Organization of WCAG 2.0

The Web Content Accessibility Guidelines (WCAG) 2.0 are organized into general principles that apply to past, present and future technologies—that is, they tend to focus more on the needs of the user than on detailing specific technical guidelines. To assist in interpreting the principles, the WCAG have also provided implementation guidelines, which address common technical implementations of the principles.

Both the WCAG 2.0 and the older WCAG 1.0 are further organized into priority levels, ranging from most important (A) to least important (AAA). At Penn State, Web sites should fulfill levels A and AA to be considered compliant.

List of Principles and Implementation Guidelines

Below is a list of principles summarizing WCAG 2.0 principles and guidelines (as of 2011), with simple implementation guidelines and links on where to find more details. These guidelines are not a list of HTML "dos and don’ts", but rather a list of accommodations that must be made for people with different disabilities.

The "How to Implement" column represents a minimum baseline for HTML, video, audio and other common technologies, although adjustments can be made as needed. Note that not every technology may be covered in these guidelines.

Principle 1: Perceivable

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

Examples of Principle 1:

  • Visually impaired users must be able to receive information via sound or touch
  • Hearing impaired users must be able to receive information via sight
  • Low vision users must be able to receive information with alternative formatting or zoomed to larger sizes
  • Color deficient users must be able to receive information without use of color

Guidelines 1.1–1.4

Synopsis of WCAG 2.0 Guidelines 1.1–1.4
Guideline Number Guideline How to Implement
Guideline 1.1:
Text Equivalent 		"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 1.1 details
Guideline 1.2:
Time Based Media (Audio/Video) 		"Provide alternatives for time-based media."

Guideline 1.2 details
Guideline 1.3:
Adaptable		 "Create content that can be presented in different ways (for example simpler layout) without losing information or structure."
  • Use appropriate semantic markup whenever possible for HTML documents, including header styles.
  • Use appropriate markup for table headers.
  • Use appropriate markup, including form LABELS, to identify form and application controls.
  • Preserve the visual sequence of content even with disabled styles.
  • Flash objects are implemented so that a screen reader will read them in the appropriate sequence.

Guideline 1.3 details
Guideline 1.4:
Distinguishable		 "Make it easier for users to see and hear content including separating foreground from background."
  • Ensure appropriate contrast between text and background.
  • Ensure that content is distinguishable independent of color.
  • Avoid automatically-playing audio, slideshows and animation. Provide play buttons instead.
  • Use CSS formatting instead of graphics to format text whenever possible

Guideline 1.4 details

Principle 2: Operable

"User interface components and navigation must be operable."

Examples of Principle 2:

  • Functions triggered via mouse or gesture are also available via a keyboard
  • All users are given sufficient time to read and use content.
  • Content does not induce seizures.
  • Users are given mechanisms to skip repetitive content.
  • Landmarks are provided to assist in screenreader navigation (e.g. meaningful page title, semantic headings, ARIA landmarks) meaningful headers and meaningful and unique link text.
  • Multiple paths are provided to navigate Web site structure.

Guidelines 2.1–2.4

Synopsis of WCAG 2.0 Guidelines 2.1–2.4
Guideline Number Guideline How to Implement
Guideline 2.1:
Keyboard Accessible		 "Make all functionality available from a keyboard." All form and application controls can be operated from a keyboard. For example:

  • Arrows keys can control sliders, or numbers can be entered to set parameters.
  • Tab keys can be used to be navigate between form fields and buttons.
  • Keyboard commands can be used to activate and operate video players.
  • Keyboard commands can be used to close and control windows.

Guideline 2.1 details
Guideline 2.2:
Enough Time		 "Provide users enough time to read and use content." When appropriate:

  • The user is warned of time limit expiration and permitted to extend time.
  • Scrolling or blinking text can be paused.
  • Users have the option to block an automatic update of content.

Exceptions are allowed when changes in timing would interfere with an essential function.

Guideline 2.2 details

Guideline 2.3:
Seizures		 "Do not design content in a way that is known to cause seizures."
  • Flashing objects should be avoided or limited to 3 flashes per second.
  • Exceptions are allowed for flashes below the general or red flash threshold.

Guideline 2.3 details
Guideline 2.4:
Navigable		 "Provide ways to help users navigate, find content, and determine where they are."
  • HTML Frames are given meaningful titles
  • Users are given mechanisms to skip repetitive content.
  • Landmarks are provided to assist in screen reader navigation,
    e.g. meaningful page title, meaningful headers and meaningful and unique hyperlink text.
  • Multiple paths are provided to navigate through Web site content.
  • Keyboard users are able to see a cursor or other indicator of position on the screen.

Guideline 2.4 details

Principle 3: Understandable

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

Examples of Principle 3:

  • Site is free of unannounced pop up windows.
  • Separate Submit or Go buttons/links are provided to initiate page changes (versus autosubmit upon selection).
  • Navigation and labels are consistent across a Web site or application.
  • Mechanisms are available to detect errors and provide clear instructions to users on fixing errors.
  • Language of text or subsection of text is identified.

Guidelines 3.1–3.3

Synopsis of WCAG 2.0 Guidelines 3.1–3.3
Guideline Number Guideline How to Implement
Guideline 3.1:
Readable		 "Make text content readable and understandable."
  • Identify language of text or subsection of text with a language code.
  • Identify and define unusual words or jargon.

Guideline 3.1 details
Guideline 3.2:
Predictable		 "Make Web pages appear and operate in predictable ways."
  • Avoid unannounced pop up windows.
  • Avoid disabling the browser’s Back button.
  • Provide a separate Submit or Go button/link to initiate page changes (versus autosubmit upon selection).
  • Allow automatic slideshows, videos and scrolling/blinking text to be paused.
  • Give users the option to block automatic updates of content.

Guideline 3.2 details

Guideline 3.3:
Input Assistance		 "Help users avoid and correct mistakes."
  • Provide appropriate form field validation.
  • Provide clear labels for form and application controls.
  • Provide usable instructions for entering information into forms and applications (preferably before the form field).
  • Provide clear and usable error messages identifying the location of error and information for correcting it.

Guideline 3.3 details

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

Synopsis of WCAG 2.0 Guideline 4.1
Guideline Number Guideline How to Implement
Guideline 4.1:
Compatible		 Maximize compatibility with current and future user agents, including assistive technologies.
  • Use validated markup
  • Label the name and role of all user interface components.
  • Identify the value for all data fields, including parameters for interface controls.

Guideline 4.1 details

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