Whenever you leave a device plugged into a wall socket, it continues to constantly draw a small amount of energy. It’s called Phantom electricity.  Usually, this is on the order of 1 to 5 watts, which means little to the utility bill. However, Consider how many devices are plugged in all the time needlessly in your home. The toaster. The cell phone chargers. The power cord for your printer and scanner. All of the stuff on your entertainment center. It all adds up.