There are two types of elevators: traction and hydraulic. Traction is more for taller buildings, over six floors or so. Ropes, traction electric motors, and counter-weights move the elevator up and down. Hydraulic elevators are for buildings that are up to five floors or so, due to the limited distance the jacks can reach. Hydraulic fluid goes through a submersible motor, and either pumps fluid into the jacks raising the elevator, or drains it into the tank lowering it. Complex electrical systems control the elevator, from the push buttons in the lobby, inside the car, fire safety, telecommunications, and so on. Of course this is a brief general description!