This book is an account of the accretion of matter by massive astronomical objects. 
    It sets out the physics of the accretion process in detail. 
    This is related to observations of the accretion phenomenon in stellar systems and galaxies. 
    The power derived through accretion processes is a dominant source of 
    emission energy in binary X-ray stars and the cores of active galaxies. 
    This book takes the physics undergraduate to a point at which it is possible 
    to start independent research, and it is suitable for graduate courses 
    as well as providing an overview for the professional astronomer.