Why use a router instead of a switch?

A router can route data to the correct network in a way that is similar to a switch's method. However, a router can also forward a message to its correct destination over the most efficient available route, to destinations far removed from the LANs to which it is connected. Switches and bridges use MAC addresses to make decisions, but for TCP/IP, routers us IP addresses to determine the path by which tp send a packet.