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Accessibility Toolkit for Open Educational Resources (OER): Accessibility Principles

Accessibility guide for creating OER

Our role in ensuring accessibility

For accessibility to become embedded in our everyday thinking and world, we all need to realize the role we all can play in accessibility.  We need to incorporate accessibility into workflows and considerations.  Try to step back and think "is X accessible? is there a way I can make Y accessible?" Ensuring accessibility does not need to be part of a person's job description or a person's personal experience and life to become something all people can participate in.  

This page covers why accessibility matters, web guidelines and descibes the four main pillars of accessibility.

Web Content Accessibility Guidelines [Updated 2023]

What is WCAG and why should you care?

  • The Web Content Accessibility Guidelines (WCAG) were created to help define how to make web content more accessible with the goal of providing a single shared standard.
  • The most recent version is WCAG 2.2.
  • WCAG 2.2 extends Web Content Accessibility Guidelines 2.1 (2018).
  • WCAG 2.2 success criteria are written as testable statements that are not technology-specific.
  • Guidance about satisfying the success criteria in specific technologies, as well as general information about interpreting the success criteria, is provided in separate documents.
  • WCAG are the most widely-accepted set of recommendations and the Revised 508 Standards are based on WCAG 2.0.
  • The W3C also encourages use of the most current version of WCAG when developing or updating Web accessibility policies.
  • When WCAG guidelines are followed they improve usability for everyone.
  • WCAG 1.0 focused heavily on the techniques for accomplishing accessibility, especially as related to HTML. 
  • Subsequent versions of WCAG focused more heavily on the principles of accessibility, making them more flexible, and encourages developers to think through the process of accessibility conceptually.
  • WCAG 2.0 is based on four main guiding principles of accessibility known by the acronym POUR perceivable, operable, understandable, and robust.
  • WCAG 2.2 was initiated with the goal to continue the work of WCAG 2.1: Improving accessibility guidance for three major groups: users with cognitive or learning disabilities, users with low vision, and users with disabilities on mobile devices.

POUR [Updated 2023]

There are four main guiding principles of accessibility upon which WCAG has been built.  These four principles are known by the acronym POUR for perceivable, operable, understandable and robust.  POUR is a way of approaching web accessibility by breaking it down into these four main aspects. Many of the technology challenges faced by disabled people/people with disabilities can be described using one of the POUR principles. Read to learn more about POUR.

Means the user can identify content and interface elements by means of the senses. For many users, this means perceiving a system primarily visually, while for others, perceivability may be a matter of sound or touch.

Perceivable problem examples:

  • A website's navigation consists of a number of links that are displayed in a different order from page to page. If a user has to relearn basic navigation for each page, how can she effectively move through the website?
  • A Word document contains a number of non-English words and phrases. If the languages are not indicated, how can assistive technology present the text correctly?

Perceivable solutions:

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.
Time-based Media
  • Provide alternatives for time-based media.
  • Create content that can be presented in different ways (for example simpler layout) without losing information or structure.
  • Make it easier for users to see and hear content including separating foreground from background.

Means that a user can successfully use controls, buttons, navigation, and other interactive elements. For many users this means using assistive technology like voice recognition, keyboards, screen readers etc.

Operable problem examples:

  • Mouse-dependent web content will be inaccessible to a person cannot use a standard mouse.
  • People with low or no vision also relay on the functionality of the keyboard. They may be able to manipulate a mouse just fine, but it doesn't do them much good because they can't see where to click on the screen. The keyboard is much easier for a person who is blind to manipulate.

Operable solutions

Keyboard Accessible
  • Make all functionality available from a keyboard.
  • Keyboard accessibility is one of the most important principles of Web accessibility because it cuts across disability types and technologies
Enough Time
  • Provide users enough time to read and use content.
  • Do not design content in a way that is known to cause seizures.
  • Provide ways to help users navigate, find content, and determine where they are.

Users should be able to comprehend the content, and learn and remember how to use your OER site. Your OER should be consistent in its presentation and format, predictable in its design and usage patterns, and appropriate to the audience in its voice and tone.

Understandable problem examples:

  • A website's navigation consists of a number of links that are displayed in a different order from page to page. If a user has to relearn basic navigation for each page, how can they effectively move through your OER?
  • A site makes use of numerous abbreviations, acronyms, and jargon. If these are never defined, how can users with disabilities (and others) understand the content?

Understandable solutions

  • Make text content readable and understandable.
  • Make Web pages appear and operate in predictable ways.
Input Assistance
  • Help users avoid and correct mistakes.

Content must be robust enough that it can be interpreted reliably by a wide variety of users, allowing them to choose the technology they use to interact with websites, online documents, multimedia, and other information formats. Users should be allowed to choose their own technologies to access OER content.

Robust problem examples:

  • A website requires a specific version of a web browser to make use of its features. If a user doesn't or can't use that browser, how can that user experience the features of the site?
  • A document format is inaccessible to a screen reader on a particular operating system. If a user employs that OS for day-to-day tasks, how can she gain access to the document?

Robust solutions:

  • Maximize compatibility with current and future user agents, including assistive technologies.

Read the actual WCAG POUR guides: Perceivable external link., Operable external link. , Understandableexternal link. and Robust external link..

Citation: [UXDX's Homer Gaines] (2022, Jan 27) The Four Principles of Accessibility (20:38) URL:

Useful Videos on WCAG and POUR [Updated 2023]

Citation: [Code Computerlove] (2023, Jan 26) Everything You Need to Know about WCAG 2.2 (28:32) URL:

Citation: [Accessible Design Jam] 10 CRITICAL Web Accessibility Updates You MUST Know, WCAG 2.2 (2023, Mar. 20) (8:41) URL:

Attribution: [Jadu] (2019, Jan. 31) Accessibility - The new WCAG 2.1 guidelines. (3:35) URL:

Attribution: [Government Digital Service] (2017, Oct. 23) POUR: The 4 principles of accessibility. (2:27) URL :