QUIC
QUIC, defined in RFC 9000, is a transport protocol that runs over UDP instead of TCP and builds the TLS 1.3 handshake into establishing a connection, rather than layering TLS on top of a separate transport handshake. A client and server exchange cryptographic and transport parameters together, so a new connection to an already-known server can often send encrypted application data after a single round trip (0-RTT), instead of waiting through a separate TCP handshake and TLS handshake first. QUIC multiplexes many independent streams over one connection, and because loss recovery happens per stream rather than once for the whole connection, a lost packet only stalls the stream it belonged to instead of blocking every other stream in flight -- the head-of-line-blocking problem TCP-based HTTP/2 cannot avoid. QUIC also identifies a connection independently of the underlying IP address and port, so a connection can survive a client switching networks, such as moving from WiFi to mobile data, without being torn down and renegotiated from scratch. HTTP/3 is the application protocol built on top of QUIC.
By AdminKit team, Netbase JSC · Updated