Delivery process where messages are cut up into packets, each packet containing the routing address; in the network nodes, these packets arrive in a queue and after analysis of the address are retransmitted on the appropriate transmission channel once the address has been analysed. On arrival, the messages are reconstituted from the received packets.
Since a packet only occupies a channel during transmission, the channel then becomes available for transmitting other packets, either from the same message or others.
The essential difference between packet switching and circuit switching is the way the intermediate forwarding nodes are managed/reserved.
Circuit switching requires communication resources to be reserved during the whole conversation on a complete path between the two machines involved in the dialogue. In contrast, with packet switching, only the section linking two forwarding nodes between which the packet is currently transiting needs to be reserved, and only during the transit of the packet between the two nodes. An obvious advantage of packet switching over circuit switching is therefore the more rational use of communication resources: the resources are only reserved while they are actually being used.