<b>This week in caching: HTTP caching headers, decoded</b>

<b>This week in caching: HTTP caching headers, decoded</b>
The headers that decide whether a return visit even hits your server:
— <i>Cache-Control: immutable</i> — the directive that tells browsers to skip revalidation entirely for fingerprinted assets; underused outside Facebook.
— <i>ETag vs Last-Modified</i> — why strong ETags break behind some proxies and when 304s actually save you bandwidth.
— <i>no-cache is not no-store</i> — the eternally confused pair, spelled out with what each does to the back button.
— <i>Vary: the foot-gun</i> — how Vary: User-Agent fragments your cache into uselessness.
Credits to Jake Archibald's caching best-practices post, still the canonical reference.
Bookmark: Archibald's piece — if you read one thing on HTTP caching this year, this.