This book on compressors with reciprocating pistons is intended to provide both students and practicing designers, planners, and operational engineers with all the knowledge necessary to understand the thermodynamic processes in the compressor and its operating behavior, as well as to calculate its energy consumption and all the main dimensions required for the design and construction of the machine. There are some misleading views on piston compressors found in the literature. To spare the reader of this book from misconceptions and unnecessary time expenditure, general references to such publications are avoided. Everything is explained in detail as necessary for understanding. The theoretical foundations include only what is directly related to the internal processes in the compressor.