packet

Any block of data sent over a network or communications link.

Each packet may contain sender, receiver, and error-control information, in addition to the actual message, which may be data, connection management controls, or a request for a service. Packets may be fixed- or variable-length, and they will be reassembled if necessary when they reach their destination. The actual format of a packet depends on the protocol that creates the packet; some protocols use special packets to control communications functions in addition to data packets.

See also datagram; frame; packet switching.