A compressor is a piece of machinery that increases the pressure of the gas ( or air), by reducing its volume. Compressors operate similarly to pumps, boost pressure and help the gas to travel through a piping system, when needed. This, in turn, allows transmitting a high volume of gas through a small size piping system
Compressors could be of different types and for various purposes. Generally, compressors fall into two main categories: 1) Positive displacement and 2) Dynamic. Those are further subdivided into various types too. In the oil and gas industry, reciprocating and centrifugal ( dynamic) compressors are mainly used.