Safe, idempotent, cacheable — the method property grid

Why you can retry a PUT but not a POST, why a crawler can GET freely, and what a cache is allowed to keep.

1. The method overview table

   The request method token is the primary source of request semantics; it indicates the purpose for which the client has made this request and

2. Safe — read-only intent (GET, HEAD, OPTIONS, TRACE)
3. Idempotent — retry-safe (adds PUT, DELETE)
4. Cacheable — a property of the response, not the method
5. The idempotency definition, and the automatic-retry rule it unlocks

   A request method is considered "idempotent" if the intended effect on the server of multiple identical requests with that method is the same