Solid State Member
A router is used to "route" packets. Not all routers have firewalls. It recieves packets and using a routing protocol determines where to deliver the packet (its Destination). Think of it like a highway with multiple exits and a traffic cope standing there, you drive up, show him your address and he routes you down the correct path. Thats bascially it. There are other functions, but that is what a router is.