A computer network (LAN or WAN) operates by connecting computers and the peripherals (like printers and scanners) using two pieces of equipment: switches and routers. The switches enable the devices in a local network to talk to each other, while the routers enable the devices to connect with external networks.
A switch acts as a controller - it manages how various devices within a local network share information among themselves. The router acts as a dispatcher - it chooses the best route for sending and receiving information across a local and an external network or Internet. Routing and switching functions are all about planning and fixing routers and switches in a network.