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ProtocolCodes
Web Standards

HTTP Semantics (RFC 9110)

The core RFC defining HTTP's architecture, including methods, status codes, headers, content negotiation, and conditional requests, independent of the wire format.

Related Protocols

HTTP

Related Scenarios

405 Method Not Allowed — Wrong HTTP Verb HTTP
431 Request Header Fields Too Large — Cookie Overflow HTTP

Defined In

RFC 9110 HTTP Semantics
RFC 7231 Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content
RFC 2616 Hypertext Transfer Protocol — HTTP/1.1

Decision Guides

Which HTTP Error Code Should I Return? Which HTTP Redirect Should I Use? Which HTTP Success Code Should I Return? Should I Cache This HTTP Response? 401 vs 403: Which One Should I Return? How to Map Errors Across Protocols Which Protocol Should I Use?

See Also

HTTP/2 HTTP Concepts
HTTP/3 HTTP Concepts
REST (Representational State Transfer) HTTP Concepts
RFC (Request for Comments) Protocol Design
URI (Uniform Resource Identifier) Web Standards
Structured Headers (RFC 8941) Web Standards
Web Linking (RFC 8288) Web Standards
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