Normally, networking is means connect the difference network into a big one. difference network is refer to the LAN in difference part of the branch of a big company, etc.

switch and router is two difference type device, switch is used for layer 2 switch mainly, but right now, switch can work as a router in layer 3 mode, but the mainly difference is performance. switch's layer 2 works better than router.

router work's in layer 3, and only have limited layer 2 funtions, it's used for routing, and have much high performance in routing than switch.