A Layer 3 data transmission technology in which messages to be transmitted are divided into a series of packets that are then sent individually across the network, not necessarily in the order they were created. At the destination the packets must be-sequenced and reassembled into the original message. Unlike circuit switching, there is no dedicated physical end-to-end connection, although some packet switching services such as X.25 operate in a logical connection-oriented mode, assuring the destination is ready before any messages are sent. IP operates in a connectionless mode.
More: Packet Switching