freswood

I've started a networks topic in yr12 IT and am a little confused by the various pieces of hardware. The book doesn't give any explanation, and tech websites are too difficult to understand with my very basic knowledge.

This is what I've been able to gather so far, and I'd be grateful if anybody could correct me where necessary:

Hub = rebroadcasts a signal down all channels
Switch = broadcasts a signal to the correct destination
Bridge = sends signals from one network segment to another, down all channels of that segment.
Gateway = apparently something like a switch..? Could somebody explain the difference? Just in very basic terminology like I've been using in the other examples.
Router = decides the best path for the packet to travel. How is it different to the other stuff?

What also confuses me is the combinations you'd use. So it'd be either a hub or a switch, and would you use a bridge/gateway? And when would you use a router?

Sorry for being so...ignorant. I'd really appreciate your help