Learn in the textbookTCP/IP and Web Protocols
DefinitionUDP is a connectionless transport-layer protocol that sends data without setting up a connection with the other side.
ExplanationBecause it neither checks whether data arrived nor resends lost data, it involves fewer steps and less delay. If missing data or out-of-order arrival must be dealt with, the application handles it. It suits traffic such as voice calls and video streaming, where avoiding waits matters more than losing a little data.
AnalogyIt is like a public announcement in a building that keeps playing without waiting for any response. If someone misses it, it is not replayed just for that person.
Memory hookIts full name is User Datagram Protocol. A datagram is a small packet sent off on its own, and the name reflects this send-and-forget nature.