Which RFC standardized the QUIC transport protocol in 2021?

Which RFC standardized the QUIC transport protocol in 2021? RFC 9000.

RFC 9000, published in May 2021, defines version 1 of QUIC, a secure, general-purpose transport protocol built over UDP. The document specifies QUIC’s core mechanisms, including streams, connection establishment, flow control, connection migration, packet protection, and version negotiation. It was published by the IETF as a Proposed Standard.

QUIC was designed to reduce some limitations associated with TCP while retaining reliable, ordered delivery through its own transport mechanisms. It integrates TLS 1.3 into the protocol, allowing encryption and transport setup to happen together. QUIC can also maintain a connection when a device changes networks, such as moving from Wi-Fi to cellular data.

RFC 9000 is not the only QUIC-related 2021 RFC. RFC 9001 describes QUIC’s use of TLS, RFC 9002 covers loss detection and congestion control, and RFC 8999 defines QUIC invariants. That is why RFC 9000 is the canonical answer for the core QUIC transport specification.