2. Understanding WCAG 2.1 in Plain Language
You do not need to memorize WCAG. You only need to know its four big ideas and what “Level AA” asks of you.
WCAG stands for the Web Content Accessibility Guidelines, published by the World Wide Web Consortium (W3C) — the international body that sets web standards. WCAG 2.1 is the version most laws and policies point to. It is organized around four principles, success criteria, and three conformance levels.
The four principles (POUR)
Everything in WCAG fits under four simple promises. Content must be:
| Principle | In plain words | What it looks like for you |
|---|---|---|
| Perceivable | People can sense it with at least one sense | Alt text for images, captions for video, transcripts for audio, good contrast |
| Operable | People can use and navigate it | Works without a mouse, no rapid flashing, enough time to read |
| Understandable | People can follow it | Plain language, clear headings, predictable layout, stated language |
| Robust | It works with assistive technology | Proper structure so screen readers and tools can read it correctly |
Conformance levels: A, AA, AAA
WCAG groups its requirements into three levels. Think of them as good, better, best:
| Level | Meaning | Who aims for it |
|---|---|---|
| A | The minimum — basic barriers removed | Absolute floor; not enough on its own |
| AA | The standard most laws and donors require | Your target throughout this handbook |
| AAA | The highest, ideal level | Specialized content; rarely required for everything |
A quick word on versions: 2.1 or 2.2?
WCAG 2.1 (2018) is the version most laws and funders reference, and the baseline this booklet is written to. WCAG 2.2 (published October 2023) is the newest version — it keeps everything in 2.1 and adds a few criteria aimed mainly at people who build websites and apps (clearer keyboard focus, larger touch targets, simpler logins). For the content you create — text, images, audio, video, posts, documents — the practices in this booklet meet both 2.1 and 2.2 at Level AA. (You may also hear about WCAG 3.0 — as of 2026 it is still an early draft, years away from becoming a standard, so 2.2 remains the version to follow.)
Meet the tools people use
Many people reach your content through assistive technology. Knowing what these tools do explains why the steps in this guide matter:
| Tool | Who uses it | What it needs from you |
|---|---|---|
| Screen reader (NVDA, VoiceOver, TalkBack) | Blind / low-vision users | Reads text and alt text aloud; needs real headings and descriptions |
| Screen magnifier | Low-vision users | Large, high-contrast text that stays readable when zoomed |
| Captions / transcripts | Deaf / hard-of-hearing users | Text version of all spoken audio |
| Voice control & switches | Users with motor disabilities | Clearly labeled, well-spaced controls |