The Free On-line Dictionary of Computing (18 March 2015):
A communications paradigm in which packets
(messages or fragments of messages) are individually routed
between nodes, with no previously established communication
path. Packets are routed to their destination through the
most expedient route (as determined by some routing
algorithm). Not all packets travelling between the same two
hosts, even those from a single message, will necessarily
follow the same route.
The destination computer reassembles the packets into their
appropriate sequence. Packet switching is used to optimise
the use of the bandwidth available in a network and to
minimise the latency. X.25 is an international standard
packet switching network.
Also called connectionless. Opposite of circuit switched
or connection-oriented. See also virtual circuit,