Virtual Circuit is a logical path between nodes in a network, typically a telecommunications network. The path is made up of discrete segments of the network that are connected using switches.
The nodes on the circuit communicate as if they were directly connected using physical wires, but the switches actually establish and tear down the virtual communication path.
You can change the logical paths within the network by simply reconfiguring the switches to establish new paths and tear down old ones - you need not manually reconnect wires to create new circuits.
There are two types of virtual circuits:
One example of WAN technology that uses virtual circuits is frame relay, which enables PVCs to be established between nodes over a public or private carrier network. Another example is X.25 networking technology.