This self-contained book begins with fundamental principles and proceeds to the latest developments in the field. Using a systematic mathematical approach, it covers linearized and transonic theories, simple flows, general theories of lift and drag, subsonic flows, sonic flows, shock waves, airfoils and three-dimensional wings. Also discussed are far fields and the transonic law of stabilization.Significant mathematical areas which enter the discussion are: Partial Differential Equations of Mixed Type, Weak Solutions (Shock Waves), Hodograph Transformations, Similarity Solutions and New Numerical Methods for Equations of Mixed Type.