This text has been designed to be used primarily by equipment users, as a guide in selecting, monitoring, and enhancing the aerodynamic performance of various types of compressors. Some basic theory is included as an aid in helping field personnel to better understand the aerodynamics of compressors so that performance enhancements and trouble resolution can be more readily realized. As much as possible, I have attempted to stick to the "business end" of the applicable aerodynamic principles. This book is the result of various books, articles, notes, seminars, and personal experience that I have collected over the years working in the field of compressor aerodynamics. As it is such a "collection," references have been used extensively as noted.