The book "fundamentals of compressible flow'' is standard textbook for introductory course of gas dynamics. This book, Fundamentals of Compressible Flow, describes the fundamentals of compressible flow phenomena for engineers and others. This book is designed to replace the book(s) or instructor's notes for the compressible flow in (mostly) undergraduate classes for engineering/science students. It is hoped that the book could be used as a reference book for people who have at least some knowledge of the basics of fundamental fluid mechanics, and basic science such as calculus, physics, etc. It is hoped that the computer program enclosed in the book will take on a life of its own and develop into an open content or source project. The software and the book can be download at www.potto.org.