HTTP foundations

Start here when a browser, cache, crawler, or proxy is receiving a response that needs to be explained. The series covers representation and method semantics, caching, redirects, compression, and discovery.

A cache sends a GET with If-None-Match and illustrative tag W/"release-a" to the origin. A matching response returns 304 so the cache can reuse its stored body; a changed representation returns 200 with a body.

Validators decide whether a cached copy is still the answer

Conditionals are the cache’s second clock; a 304 means the stored copy is still the answer.

Method, selected bytes and cache form a client evidence journey; the same representation selection connects comparisons.

Read a live edge the way a client does

Walk a live origin from method to body to cache, and leave with checks you can reuse.