cache-control
termweb dev
The header that tells caches whether a response may be stored, by whom, and for how long.
Two mistakes recur and both are expensive. Caching something private in a shared cache serves one user's page to another, which is a data breach caused by a header. And caching nothing means every request reaches the origin, which turns a traffic spike into an outage that a correct directive would have absorbed entirely. The directive is small, sits in one place, and decides both.
Also known as: caching headers