Use HTTP terms consistently

Start with a concise definition, then follow the related lesson, reference, or primary specification when you need the complete rule.

Reviewed terms

Term
Cache validator
Representation metadata used to determine whether a stored representation corresponds to the selected current representation.
Term
CORS preflight request
A browser-generated OPTIONS request that asks whether a cross-origin method and non-safelisted request fields are allowed.
Term
Freshness lifetime
The time between a response's generation and expiration, calculated from explicit cache metadata or an allowed heuristic.
Term
Idempotent method
A method whose intended effect on the server is the same for one request as for multiple identical requests.
Term
Intermediary
A participant between an HTTP client and server that relays messages, sometimes with caching or transformation behavior.
Term
Origin
The scheme, host, and port tuple used as a browser security and resource-sharing boundary.
Term
Representation
Representation metadata and representation data that reflect resource state within the semantics of an HTTP message.
Term
Safe method
A request method whose defined semantics are essentially read-only from the client's requested intent.