Power lines are wires that conduct electricity through to another place. Many have transformers. The voltage of the power at the end is usually 100V (Japan), 120V (North and Central America, parts of South America and Africa, and Saudi Arabia), or 220-240V (most of the rest of the world), but is much higher while going through the electric power transmission lines. The power at the end is then safe enough to be used when "stepped-down" by a transformer. 