Source : Free On-Line Dictionary of Computing

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.,
        August 1980].
     
        (1998-02-11)