datagram

A packet of information passed between two communicating processes across a network. Both the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) are indirectly involved in sending datagrams to provide reliable or unreliable communication, respectively.

A packet of data, such as a "UDP" message, that (from the viewpoint of the programs involved) can be sent independently over the network. (In fact, all packets are sent independently at the "IP" level, but "stream" protocols such as "TCP" hide this from your program.)

In packet switching, a self-contained packet, independent of other packets, that contains information sufficient for routing from the originating data terminal equipment (DTE) to the destination DTE without relying on prior exchanges between the equipment and the network. Note: Unlike virtual call service, when datagrams are sent there are no call establishment or clearing procedures. Thus, the network may not be able to provide protection against loss, duplication, or misdelivery.