RFC (Request for Comments)

A formal document published by the IETF (Internet Engineering Task Force) that defines internet standards, protocols, and best practices. Key RFCs include RFC 9110 (HTTP Semantics), RFC 5321 (SMTP), RFC 959 (FTP), RFC 1035 (DNS), RFC 6455 (WebSocket), and RFC 3261 (SIP). RFCs are the authoritative source for protocol behavior and status code definitions.