The physics and dynamics of planetary nebulae are surveyed in this comprehensive monograph. The topics covered include processes occurring in the highly ionized gaseous medium, the formation of emission lines in rather specific conditions, continuous emissions extending from radio frequencies and infrared up to ultraviolet and X-rays, and methods of deciphering the observed spectra and detecting the physical and kinematic parameters of the radiating medium. Many of these methods have become powerful tools for the study of various other cosmic objects from stellar atmospheres to galactic nuclei. Special attention is paid to discoveries made using space observations. The problems of the origin of planetary nebulae and their evolution are discussed extensively. A catalogue of planetary nebulae by excitation classes is also included. The book should remain a standard reference for students and researchers in the field for years to come.