Compressed air

Compressed air is air stored under a pressure that is greater than atmospheric pressure. It is generally produced by an air compressor.
Uses.
Compressed air may be used for transfer of energy in industrial processes. Compressed air is used to power pneumatic tools. Compressed air is used to spray paint, to operate air cylinders for automation, and to propel vehicles. Railway brakes applied by compressed air make train travel safer. Compressed air brakes are also found on large road vehicles, such as trucks and buses.