Who the Web Is For

Somewhere right now a person is reading a web page without seeing it, another is filling in a form without a mouse, and a third is watching a video on a silent train. Each of them is using the web with a disability or a limitation, and each of them hits the same wall when a page is built carelessly. Accessibility means that people with disabilities can perceive, use and understand what you build, with the tools they already use.

Think of the ramps and lifts in a building. They were put there for wheelchair users, and every day they are used by parents with prams, travellers with suitcases and delivery staff with trolleys. Web accessibility works the same way: the work done for one group quietly helps many more. On the web, though, the ramp is not an extra you add later. It is how the page is built in the first place.

This chapter gathers the habits the book has been building since Chapter 2 into one discipline, and names the standard behind them.

Who Are "People with Disabilities"?

The group is much larger and more ordinary than most beginners imagine. The World Health Organization estimated in 2023 that about 1.3 billion people, roughly one in six people on Earth, live with a significant disability. Many more have milder limits that grow with age: eyes that need larger text, hands that shake a little, hearing that fades.

It helps to sort limitations into three kinds. A permanent one lasts: someone who is blind, deaf, has limited movement in their hands, or thinks and reads differently, for example with dyslexia. A temporary one passes: a broken arm in a cast, eyes dilated after a visit to the optician. A situational one comes from the moment: bright sunlight on a phone screen, a baby held in one arm, a noisy train with no headphones.

The third kind is why accessibility is not a question about other people. Everyone moves through situational limits every week, and a page that works for a blind reader or a one-handed user usually works better for everyone else in those moments too.

How Do They Use the Web?

People with disabilities use the same browsers you do, often with one more piece of software or hardware in between. The general name for that extra layer is assistive technology. A few kinds matter most to a page author.

A screen reader reads the page aloud, or sends it to a braille display, and lets the user jump between headings, links, landmarks and form fields. Blind users rely on one, and so do many people with low vision or reading difficulties.

A screen magnifier enlarges part of the screen, sometimes ten times or more, so the user sees only a small piece of the page at a time. Browser zoom does a gentler version of the same job for millions of people who need bigger text.

Many people use the keyboard only, because a mouse needs a steady hand. Others use a switch, a single large button pressed with a hand, a foot or the head, which steps through the page one control at a time. Voice control lets people say "click Send" instead of pointing. And captions put speech in video into words for people who are deaf or hard of hearing.

Each of these tools depends on the page telling it the truth: what each part is, what it is called, and what it does. That is what the HTML you have written since Chapter 2 provides.

Who	How they browse	What the page must provide
Blind	a screen reader, by headings, landmarks and links	real elements, alt text, labels, a sensible order
Low vision	zoom, a magnifier, high-contrast settings	enough contrast, text in rem, a layout that reflows
Limited hand movement	keyboard, switch, voice control	every control reachable by keyboard, visible focus, large targets
Deaf or hard of hearing	captions and transcripts	captions on video, no information carried by sound alone
Situational	one hand, bright sun, no sound	all of the above; it helps everyone at once

What Is WCAG?

You need a shared definition of "accessible", or every team would invent its own. That definition is WCAG, the Web Content Accessibility Guidelines, written by the W3C, the same standards body you met in Chapter 1. The current version is 2.2, published in 2023. It is a list of testable rules, each called a success criterion, such as "text has enough contrast against its background".

The rules are grouped under four principles, and each one is a question you can ask of any page. Perceivable: can every user take in the content, whatever their senses? Operable: can every user work every control, whatever they press or say? Understandable: is the content and its behaviour clear and predictable? Robust: is the page built from real, standard parts that browsers and assistive technology can interpret?

Each success criterion also has a level. Level A is the floor: without it, some people cannot use the page at all. Level AA adds the criteria that remove the most common serious barriers, such as low contrast. Level AAA is the strictest, and the W3C itself does not recommend requiring it for whole sites, because some content cannot meet it.

When people say a site "meets WCAG AA", they mean it passes every level A criterion and every level AA criterion. That is the usual target for professional work, and it is the target this book has been building towards.

Is Accessibility Optional?

Often, legally, it is not. In the European Union, the European Accessibility Act has applied since June 2025 to many online shops and services, and the standard it relies on points to WCAG level AA. In the United States, the rule for state and local government websites points to WCAG AA as well, and the Department of Justice treats the websites of businesses open to the public as covered by the same disability law. Other countries have similar laws. A personal site is rarely covered, but the sites you build for an employer or a client often are.

There is a plainer argument too. A page that some visitors cannot use is a broken page, in the same way as a page with a link that goes nowhere. Accessibility is part of whether the thing works, not a decoration on top of it.

What Has the Book Already Done?

This chapter does not start from zero, because the book has built the accessible version of everything from the first page. Here is the trail so far:

• Alt text on images, and an empty alt for decoration, in the images topic of Chapter 2.
• Landmarks such as header, nav and main, in Chapter 2's topic on semantic structure.
• A visible focus style with :focus-visible in Chapter 3, checked on every control in Chapter 9.
• Real buttons instead of clickable boxes, also in Chapter 9.
• A label for every form field, in Chapter 10.
• Error and success messages that screen readers announce, in the contact form of Chapter 10.

The next three topics add the pieces that were missing: how assistive technology actually reads a page, the measurable visual rules, and how to test all of it.