What does it mean?
Accessible experiences support keyboard input, readable contrast, semantic structure and clear focus behaviour. Accessibility is a design and implementation concern, not merely a final compliance check.
Make it concrete.
Illustrative example: Someone navigating a shopping site by keyboard can reach every filter, tell which filter is selected, and see where keyboard focus is.
A common mistake.
Assuming a high contrast palette alone makes a product accessible.
When should you use it?
Throughout design and development; especially for reusable components and important user tasks.
Explore the source.
W3C — WCAG Overview ↗This is a reference for further learning, not an endorsement or a verbatim quotation.