What is React context and when should you use it instead of prop drilling?

Context provides a way to pass data through the tree without threading props through every level. Use it for broadly needed, moderately stable values like theme, auth session, or locale—not as a replacement for all state management or for high-frequency updates without care.

Context updates re-render all consuming components unless split into multiple contexts or combined with selectors/memoization patterns. Prop drilling is fine for shallow, localized data.