Learning paths
Curated routes through the material — start here.
What actually governs HTTP today
orientation
The 2022 core (RFC 9110/9111/9112) replaced a decade of RFCs. Here's the lineage and why it was redone.
6 stops
The requirement keywords: MUST, SHOULD, MAY
foundation
Every IETF spec runs on these words. Reading them wrong is the #1 way implementations diverge.
5 stops
Safe, idempotent, cacheable — the method property grid
foundation
Why you can retry a PUT but not a POST, why a crawler can GET freely, and what a cache is allowed to keep.
5 stops
You never GET a resource
foundation
Resource vs representation vs message — the abstraction that makes content negotiation, caching, and ETags all make sense.
5 stops