User Data-gram Protocol provides a connection-less data-gram service that offers best-effort delivery, which means that UDP does not
guarantee delivery or verify sequencing for any datagram’s. A source host that
needs reliable communication must use either TCP or a program that provides its
own sequencing and acknowledgment services. The user data-gram protocol is a most important protocol of the TCP/IP suite and is used to send the short messages
known as data-gram. Common network applications that uses UDP are DNS, online
games, IPTV, TFTP and VOIP. UDP is very fast and light weight. UDP is an
unreliable connection-less protocol that operates on the transport layer and it
is sometimes called Universal Data-gram Protocol.