Four Principles for Accessibility 

WCAG’s four principles for accessibility found in WCAG’s Quick Reference Guide. They are grouped under Perceivable, Operable, Understandable and Robust.

Read below for a quick overview of  the guidelines:


This principle ensures there are alternative ways of accessing content.

  • Non-text content should have text alternatives so that it can be accessed via screen readers. If you have audio recordings, you should provide a text version that screen readers can access.
  • Video recordings should be captioned.
  • Web content should be organized so that it is easily parsed by screen readers. If content needs instructions to operate and understand, those instructions should not “rely solely on sensory characteristics of components such as shape, color, size, visual location, orientation, or sound.”
  • For those who are visually impaired, contrast is very important. A color scheme that looks great to you might not have the required contrast. Be aware that 1 in 12 men are color-blind and 1 in 200 women are color-blind.
  • Color should not be the only way to convey information.
  • If the web page has video, there should be an easy way to pause, replay and play.
  • There should be an easy way to increase font size.
  • Images should be added with “alt” tags so screen readers can explain what the image looks like.
  • People with disabilities should incur no loss of understanding or functionality due to scrolling.


  • Functionality should not depend on a pointing device. Keyboards should suffice to find content. Input fields should be accessed via tabbing.
  • Keyboard shortcuts should be able to be remapped, active only on focus, or simply turned off.
  • There should be no time limit in viewing content.
  • There should be no dynamic content that induces seizures.
  • Web pages should be titled to reflect content.
  • Headings and labels should accurately describe content.
  • Functionality used to access other parts of the site can be turned off if needed for screen readers to function.


  • Web page should indicate the language used (i.e. “lang=en”).
  • Language should be understandable, free from jargon and unexplained abbreviations.
  • Content should be predictable: “on focus” and “on input” should not change the web context.
  • Navigation and components should be consistent.
  • Errors should show error codes and descriptions. Labels or descriptions should guide input. Suggestions should guide users to successful form completion.


  • Content should parse correctly, elements should have start and end tags, elements should not have duplicate attributes, and ids should be unique.
  • User interface components like forms, links and scripts should be able to be programmatically identified. Users can set states, properties, and values programmatically and notification of these changes should be available to user agents, including assistive technologies.

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