Unit VI · People and rules
Pages everyone can use
Accessibility means people who use screen readers, keyboards, zoom or high contrast can use your app too. A few checks catch the most common failures in AI-built pages.
The standard
The Web Content Accessibility Guidelines (WCAG) 2.2 are a W3C Recommendation. They are organised under four principles: content must be perceivable, operable, understandable and robust.
Four checks with the biggest payoff
Images that carry meaning need text alternatives (alt text). Every form field needs a label tied to it, not just placeholder text. Everything must work with the keyboard alone: Tab to move, Enter or Space to act, with a visible focus outline. Normal-size text needs a contrast ratio of at least 4.5 to 1 against its background for level AA.
Test it yourself
Put the mouse away and use your app with the keyboard only. Zoom the page to 200%. Run an automated checker, and remember that it finds only some problems: a page can pass the tool and still be hard to use.
Words to know
- WCAG
- the W3C's Web Content Accessibility Guidelines
- Alt text
- a text alternative for an image
- Label
- the visible name tied to a form field
- Contrast ratio
- how far apart text and background colours are in lightness
Sources
- W3C: Web Content Accessibility Guidelines (WCAG) 2.2
- W3C: Understanding Success Criterion 1.4.3, Contrast (Minimum)
Checked October 17, 2026. Pages on other sites change; if a source no longer says what the lesson says, the source wins.