Switch
In computer networking, a switch connects multiple network devices together to form a LAN. A switch works by filtering and forwarding packets between LAN segments, transparently bridging them.
A switch is essentially a more efficient, sophisticated hub.
A switch is often confused with a router, but the two serve very different purposes. A router determines the best way to route packets across networks, based on certain network conditions.
Analogy
A good analogy for switches and routers is to think of a network of computers as a neighborhood. The switches are the streets, which connect the houses, and the routers are intersections, which contain information about the streets, like street name signs.