The Free On-line Dictionary of Computing (18 March 2015):
User Datagram Protocol
(UDP) Internet standard network layer,
transport layer and session layer protocols which
provide simple but unreliable datagram services. UDP is
defined in STD 6, RFC 768. It adds a checksum and
additional process-to-process addressing information [to
what?]. UDP is a connectionless protocol which, like TCP,
is layered on top of IP.
UDP neither guarantees delivery nor does it require a
connection. As a result it is lightweight and efficient, but
all error processing and retransmission must be taken care of
by the application program.
Unix manual page: udp(4).
[Postel, Jon, User Datagram Protocol, RFC 768, Network
Information Center, SRI International, Menlo Park, Calif.,