UDP "User Datagram Protocol", is a protocol that works in the transport layer in OSI protocol suit. It is a connection-less, unreliable, and lightweight transport layer protocol.

It does not guarantee reliable data delivery. Packets may be lost, duplicated, or delivered out of order, and there is no mechanism for re-transmission or error checking.

UDP is suitable for real-time applications like Voice over IP (VoIP), video streaming, online gaming, and internet telephony. This is because these applications can tolerate some packet loss, making UDP a more suitable choice than the connection-oriented and reliable Transmission Control Protocol (TCP).