UDP is User Datagram Protocol - one of the primary components of the Internet Protocol Suite, the set of network protocols used for the Internet. UDP provides computer applications with the possibility to send messages (datagrams) to other hosts on an Internet Protocol (IP) network with a minimum of protocol mechanism.
UDP reliability and comparison of UDP and TCP
UDP work is based on a simple transmission model without implied handshakes for reliability, ordering, or data integrity. As a result UDP is an unreliable service and messages may arrive out of order, missing or duplicated. UDP presupposes that error checking and correction is performed in the application or is unnecessary. Time-sensitive programs usually use UDP because they prefer to drop packets rather than wait for delayed ones, which may not be a good choice in a real-time system.
UDP is also useful for servers answering small queries from large number of clients. UDP, unlike TCP, is compatible with packet broadcast and multicasting.
UDP programs use datagram sockets to establish host-to-host communications.
Some historical facts about UDP:
1980 - UDP was designed by David P. Reed and formally defined in RFC 768.