HTTP Caching Strategies

The fastest network request is often the one that does not need to travel to the origin server.

HTTP caching stores a response so that a later request can reuse it. A cache hit can avoid network round trips, application processing, database queries, and repeated transfer of the response body. Caching can therefore improve latency, reduce bandwidth consumption, and protect an origin during traffic spikes.

Those benefits depend on correctness. A cache that serves one user's account data to another user is a security incident. A cache that keeps an old product price for a day is fast but wrong. Effective caching is a policy decision about what may be stored, which requests may share a response, and how long that response remains usable.