It's like Gill says - your router is a little box of tricks that plugs into the phone socket and does all the "behind the scenes" stuff - bouncer on the door, signalling away at your 'puta. Then you can be onlineanywhere in the house - more than one 'puta at a time. S'great!
I'm really uselesss with technical thingies, but a good friend set it all up for us, and I love it. Am still trying to get the hang of pictures though (said friend's on his hols at the moment....!)