UDP (User Datagram Protocol)
A connectionless transport protocol that sends discrete datagrams without establishing a session, guaranteeing neither ordering nor delivery. Because UDP skips the three-way handshake and has no retransmission logic, it offers significantly lower latency than TCP — making it the transport of choice for DNS queries, WebRTC media, and QUIC. Applications built on UDP must implement their own reliability mechanisms when packet loss is unacceptable.