In network terms, a switch is a network device that determines the path the packet should take to send the data from one point to another. A switch is similar to a router, but a switch is much simpler and faster and has the knowledge of the network and is used to determine the route of the network packets.
Switches are found at gateways where one network connects to another network where there is a large amount of data transfer.
Simple networks do not often need a switch as there might not be a large number of points in the network. Switching is of two types, Circuit Switching and Packet Switching, the former is used on telecommunications and the latter is used mainly on corporate networks and internet.