Packet switching breaks down data into smaller blocks and sends one packet at a time, while circuit switching maintains a connection until all data is sent. (Photo credit: Markus Spiske)
What is the difference between circuit-switched and packet-switched networks? To begin to answer this question, each term needs to be defined.
Circuit switching is defined as a connection between two devices on a network that use a temporary, dedicated communications channel to connect. The first example of this was with with some of the first analog telephone networks. In that case, a continuous circuit was maintained during the duration of the phone call, and the circuit was terminated when the call ended.
Some examples of technologies that use/used circuit switching:
POTS - plain old telephone service
ISDN - Integrated Services Digital Network
BRI - Basic Rate Interface
PRI - Primary Rate Interface
Conversely, packet switching is defined as transferring data using smaller packets of data, so the connection between two devices is only used for that packet, and then is freed up for other devices to send packets along the connection. This method is used today to in modern networks limit latency and increase bandwidth efficiency.
Examples of technologies that use packet switching:
Frame Relay Networks
X.25 Networks
ATM - Asynchronous Transfer Mode
MPLS - Multiprotocol Label Switching