Web Content Accessibility Guidelines, What are the four major categories?

If you are familiar with online accessibility and you like and create Web design, chances are you have come across the World Wide Web Consortium’s Web Content Accessibility Guidelines 2.0. Often referred to as WGAG 2.0, this is a set of standards that has been at the core of goals and efforts to create a more accessible internet since its inception back in 2008. The Web Content Accessibility Guidelines has undergone an array of updates and revisions, WCAG 2.1 update in 2018 being the most notable. However, the core principles staying relatively stable. That being said, we are going to take a closer look at this concept, more specifically, it’s four major categories.

At the heart of Web Content Accessibility Guidelines, standards are four key areas that keep sites usable and accessible for people of all abilities. An accessible site needs to feature perceivable, understandable, robust and operable content. These are, obviously, relatively broad terms, and so, let us break them down and get to see the manner in which they can be put into practice.


At the most basic level, people should be able to process information. Info that’s not published in a processable is regarded to as non-accessible. This, in addition to other affordances, implies providing audio for individuals who can’t see, and text for individuals who cannot hear. This does not imply providing audio for every text, but simply making the content consumable by screen readers and other assistive technologies. Apps and sites that need hearing or sight will not pass this test of perceivability.

Simply ask yourself, is there anything that a deaf, blind, color blind or low vision individual wouldn’t be able to perceive.


If people can perceive and operate a site, it does not imply that they can comprehend it. Websites that are understandable utilize clear and concise language and ideally offer functionality that’s easy to understand and concise language. If a person takes an action, the action and result connection has to be obvious. Navigation needs to be utilized consistently across a website. The forms have to follow a logical flow and give clear labels. Simply put, there should be enough guidance. This might sound more like usability rather than accessibility, but that is because usable platforms tend to be more accessible.

In this regard, you should ask if your text is clearly written and whether or not the interactions are easy to comprehend.


Individuals with disabilities need to be able to use sites and apps with an array of tools. Many people with disabilities can’t operate a mouse and so, alternatives such as keyboard-based operations should need to be implemented.

To help people with cognitive disabilities run a site, media and animations need to be controllable, and time limits for doing tasks configurable or generous. More importantly, apps and websites need to be forgiving. Everyone, even those without disabilities, make mistakes. Give instructions, warnings, cancellation options, and even second chances in order to help everyone.

In this regard, you need to ask yourself whether all functions in your site can be done with a keyboard. Can everyone control all interactive aspects of your site, and does it make doing things easier?


People choose their own mix of tech. As such, sites need to work properly across all browsers, devices, and platforms to account for user needs and personal preference. While you can’t expect a site to support the first version of Internet Explorer, websites shouldn’t dictate the technology that people can utilize. If this was the case, then it would limit access to any non-conforming internet user. Following development standards and conventions is one of the best ways to ascertain robustness. Clean code is way more consumable and robust across or platforms and devices.

David Lopresti

David LoPresti, co-owner of ADA Compliance Professionals, brings years of architectural design and ADA compliance experience to the table. With a mother who has had a life-long disability, he has seen first-hand the complexity and challenges of making a property ADA compliant. This experience has led to him dedicating his life to improving ADA access for businesses across California so they can be enjoyed by all.

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