Learn to power small networked devices (like security cameras) with an Ethernet cable
Quick, how many cables go into the back of a wireless (a.k.a. Wi-Fi or 802.11) netcam? That would be one: a power cord.
How many cables go into the back of a wired netcam, which hooks directly into your ethernet? Also one, if you´re using PoE (power over ethernet). PoE takes advantage of the fact that only two of the four twisted pairs of wire (connected to pins 1/2 and 3/6) in a standard Cat5 ethernet cable carry signals. The other four wires are available to deliver power to your camera or whatever other AC-powered device you have on the network.