What is Web Accessibility?

Understand why accessibility matters, who benefits, and the standards that guide inclusive web design.

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Why web accessibility exists

Web accessibility — often abbreviated as "a11y" (the "11" stands for the eleven letters between the "a" and the "y" in "accessibility") — means designing and building websites so that everyone can use them, regardless of ability, disability, or situation. The web was invented to be universal. Tim Berners-Lee, the inventor of the World Wide Web, said: "The power of the Web is in its universality. Access by everyone regardless of disability is an essential aspect." Yet billions of web pages are built in ways that lock people out — images without descriptions, forms without labels, content that only works with a mouse. Accessibility is the practice of removing those barriers.

This is not a niche concern. Over one billion people worldwide live with some form of disability — that is roughly 15% of the global population. When a website is inaccessible, it is not just inconvenient; it can prevent someone from applying for a job, ordering groceries, accessing healthcare information, or participating in education. Web accessibility is a fundamental human rights issue, and in many countries it is also a legal requirement.

The good news: most accessibility improvements are straightforward HTML and CSS practices you can learn right now. They do not require special tools or frameworks. They make your site better for everyone — not just people with disabilities.

Think of it this way: Think about curb cuts — those small ramps at the edges of sidewalks. They were originally designed for wheelchair users, but they also help people pushing strollers, delivery workers with hand trucks, travelers with rolling suitcases, skateboarders, and anyone with a temporary injury using crutches. Making sidewalks accessible to wheelchairs made them better for everyone. Web accessibility works the same way — features designed for people with disabilities end up helping all users. This is called the "curb cut effect."

Web Standard

The Web Content Accessibility Guidelines (WCAG) are the international standard for web accessibility, published by the W3C (World Wide Web Consortium — the same organization that maintains HTML and CSS standards). WCAG 2.1 defines three conformance levels: A (minimum), AA (recommended for most sites), and AAA (highest). Most laws and policies worldwide reference WCAG 2.1 Level AA as the baseline requirement.

Tip

"a11y" is a numeronym — a word where a number replaces letters. The "11" represents the eleven letters between "a" and "y" in "accessibility." You will see this abbreviation everywhere in developer communities, documentation, and tools.

Learn more on MDN

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