What is powerline networking and how do you use it?

What is Powerline Networking?
Powerline networking bridges the gap between wired and wireless connections. It makes use of the preexisting electrical wiring in a building, as opposed to broadcasting network data into the air or through cables snaking along baseboards. Furthermore, it has the greatest range of the three, though its effectiveness is highly dependent on the quality of the wiring and the total pulling power of the connected devices.