Compressed air tools are powered by air compression, which is supplied by an air compressor connected to the tool with an air hose. The air compressor creates power by condensing and compressing air to as little as 1/8 its original volume. As the air attempts to expand to its original volume, it creates energy that is harnessed as power. A compressed air tool is also called a pneumatic tool. Examples of a compressed air tool include a nail gun, wrench, drill, and hammer, though this is by no means an exhaustive list.