Accessibility

Accessibility answers one question:

Can someone use this with assistive tools, a different input method, or a different ability?

It is specifically about people with disabilities being able to perceive, understand, navigate, and interact with a product on equal terms, whether they use a screen reader, only a keyboard, a switch, voice control, magnification, or captions. This is the ability half of designing for everyone. The context half, language, culture, device, affordability, confidence, belongs to the sibling inclusive-design skill. They overlap but have different focuses; keep them distinct so neither gets diluted.

When to use

Use this skill when the task involves any of: WCAG conformance, ARIA, semantic markup, screen-reader support, keyboard/focus management, color contrast, text alternatives (alt text, captions, transcripts), accessible forms and error messages, target sizes, timing/timeouts, motion sensitivity, or cognitive accessibility. Also use it whenever someone asks to "make this accessible," run an a11y audit, or check whether a disabled user can complete a task.

When not to use it: if the real concern is who gets left out by context, non-English speakers, people on cheap phones or slow networks, people who can't afford data, first-time or anxious users, or global name/address formats, that is inclusion, not accessibility. Switch to the inclusive-design skill.

The mental model: POUR

WCAG organizes all of accessibility under four principles. Use them as your audit lens, every issue you find maps to one of them.