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What Are The Fundamentals Of Web Accessibility?

Sep 21, 2021

The basic definition of web accessibility is fairly straightforward: It’s the practice of making design and development decisions that accommodate people with disabilities. 1 in 4 adults in the US lives with at least one disability, per the US Centers for Disease Control and Prevention (CDC), so accessible web design is an important practice for all content creators.

Web accessibility helps to make the internet a more useful resource for everyone — regardless of whether they live with disabilities. Organizations that develop and maintain accessible web content enjoy higher customer retention rates, improved search engine rankings, and dozens of other benefits.

However, web accessibility is a mindset, not a one-time project. Whether you’re developing a new domain or updating an established website, you’ll need to understand some of the fundamental concepts of accessibility in order to develop an effective approach. 

Website accessibility requires a principle-based approach

Disabilities can change how people interact with the internet, but those changes aren’t always predictable. For example, some people with low vision use screen magnifiers; others may use screen readers to convert text to audio or braille. Some people use a keyboard alone — no mouse — to browse, while others use touchscreens or eye-gaze devices. 

Ideally, website content should be accessible for all of these users. Simple checklists of technical criteria can’t reasonably accommodate everyone.

The Web Content Accessibility Guidelines (WCAG) are the most widely cited international standards for web accessibility. While WCAG includes specific checkpoints and recommendations, it uses a principle-based approach. Organizations should understand those principles — they’re extremely helpful when making decisions about design and development. 

Read: Accessibility Is Not a Checklist

The “POUR" principles provide an excellent introduction to accessibility

Currently, all WCAG success criteria are organized according to the project’s four principles. These principles can be applied to any type of content to create a better experience for every type of user.

Per the guidelines, accessible content should be: 


All of the site’s components and information must be presented to users in a way that they can perceive. For example, if an image doesn’t have associated alternative text, people with vision disabilities couldn’t perceive the content — but well-written alternative text provides access to that information.


Users must be able to operate the content’s interface. For example, if a website cannot be operated with a keyboard alone, some visitors won’t be able to use it. Your website should not require actions that some users can’t perform — these barriers can limit your site’s reach and create a poor experience for some visitors.


Users should be able to understand the content and interface. If your content contains industry jargon, it may not be understandable for all readers. The “understandable" principle also applies to user interaction elements, semantic markup, and other elements of your site.


Users must be able to access the content with different technologies. Websites should provide the same information and interactivity regardless of whether a visitor chooses to use a screen reader, touchscreen, or a web browser.

Every person who works on your website should understand these basic principles. Designers, developers, writers, and customer care representatives play important roles in creating an internet that works for everyone.

By developing your knowledge of WCAG’s core values, you’ll be able to design and maintain your website more effectively. Accessible websites have clean, efficient code, so long-term maintenance can be significantly less expensive when accessibility is a development priority. 

Read: What Are the Four Major Categories of Accessibility?

Web accessibility requires regular testing

Earlier in this article, we discussed a few ways that disabilities could change how people interact with websites. However, one of the fundamental concepts of web accessibility is that user behavior is unpredictable — real people may prefer to change their browser settings, adjust their computer monitors, install third-party accessibility tools, or use thousands of other tactics to access the internet comfortably. 

The WCAG framework was created to remove barriers for all of these users. The guidelines provide an invaluable resource for developers, designers, and content creators, but accurate testing is essential. Automated testing tools can be helpful for finding specific types of issues, but human evaluators play a key role: Manual tests can identify accessibility barriers that affect their actual browsing experience.

The Bureau of Internet Accessibility uses a four-point hybrid testing system that includes full manual testing performed by experts using assistive technologies. We believe that automated tests can be useful, particularly at the beginning of an accessibility initiative — but web accessibility directly affects how your audience perceives your organization, and comprehensive testing provides the best path forward.

Use our free Website Accessibility Checker to scan your site for ADA and WCAG compliance.

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