Your air conditioner consists of three main parts: the evaporator; the compressor; and the condenser.
The evaporator is the indoor unit that takes in hot air from the outside and cools it. The condenser and the compressor, on the other hand, are both located outside the house. The former reverts the hot gas back to a liquid form and starts the process over again, while the latter circulates the refrigerant through the copper coils of the evaporator and the condenser.