What does 'UDP' stand for?

UDP stands for User Datagram Protocol. It is a transport-layer protocol in the Internet protocol suite that sends independent datagrams between applications without first establishing a connection.

Unlike TCP, UDP does not guarantee delivery, ordering, or duplicate protection. It also does not automatically retransmit lost data or manage a connection with a handshake. This makes UDP lightweight and fast, but it places responsibility for any needed reliability on the application using it. UDP still includes port numbers for directing traffic to the correct application and a checksum for detecting certain transmission errors.

UDP is commonly used when low delay matters more than perfect delivery. Voice calls, live video, online games, DNS queries, and DHCP commonly use UDP. A dropped packet in a conversation or game may be preferable to waiting for a delayed retransmission. The abbreviation is sometimes mistakenly expanded as “User Data Packet” or “Universal Data Protocol,” but neither is correct.