Accessibility

What it is

Web accessibility (a11y) is the practice of making digital products usable by all people, regardless of their abilities. It's not an optional feature — it's a fundamental quality requirement.

WCAG (Web Content Accessibility Guidelines)

International standard with three levels:

• A: minimum (basic contrast, alt text)
• AA: recommended (4.5:1 contrast, keyboard navigation)
• AAA: optimal (7:1 contrast, simple language)

POUR principles

1. Perceivable: perceptible content (alt text, contrast, captions)
2. Operable: keyboard navigable, no focus traps
3. Understandable: clear language, predictable behavior
4. Robust: compatible with assistive technologies

Essential practices

• Semantic HTML (<nav>, <main>, <button>)
• ARIA roles and labels when HTML isn't enough
• Complete keyboard navigation
• Sufficient color contrast
• Alt text for images
• Visible and logical focus

Quick checklist by WCAG level

Criterion	A	AA	AAA
Alt text on images	✓	✓	✓
Color contrast	3:1	4.5:1	7:1
Keyboard navigation	Basic	Complete	Complete + shortcuts
Video captions	✓	✓	✓ + audio description
Text resizing	Up to 200%	Up to 200%	No content loss
Page language	Declared	Declared	Simple and clear

Most regulations (ADA, EN 301 549, EU Accessibility Act) require level AA as a minimum.

Tools

• axe DevTools, Lighthouse (auditing)
• NVDA, VoiceOver (screen readers)
• eslint-plugin-jsx-a11y (linting)

Why it matters

Accessibility is not a nice-to-have — it is a legal requirement in many jurisdictions and an engineering practice that benefits all users. An accessible site works better with screen readers, keyboards, slow connections, and diverse devices. Ignoring it is technical debt that accumulates.

References

• WCAG 2.2 — W3C standard.
• A11y Project — Practical resources.
• WAI-ARIA Authoring Practices — W3C, 2024. Accessible design patterns and widgets.