Topic
HTTP caching
HTTP caching lets a client or intermediary reuse a stored response under defined rules.
At a glance
- Policy header
- Cache-Control
- Common validator
- ETag
Overview
HTTP caching lets a client or intermediary reuse a stored response under defined rules. Cache directives describe whether and how a response may be reused, while validators let a client ask whether a previously stored representation still matches the server's current version.
Freshness and validation
A fresh response can be reused according to its policy. A stale response may need validation before reuse. Validators support conditional requests that avoid transferring unchanged content unnecessarily.
Public and private data
Shared caches can serve multiple users, so personalized responses need an appropriate policy. A caching decision must reflect who may see the content as well as how frequently it changes.
Sources and review
MOOR's explanatory text is supported by the following source links.
- HTTP caching — MDN Web Docs
- Cache-Control reference — MDN Web Docs