Planetary nebulae present a range of shapes and morphologies. They are ideal laboratories for the study of different astrophysical processes: atomic physics, radiative transfer, stellar winds, shocks, wind-wind interaction, and the interaction between stellar winds and the interstellar medium. In addition, planetary nebulae provide information about the late stages of stellar evolution. In the mid-1990s studies of planetary nebulae have progressed rapidly and new phenomena and insights have been gained. This is partly due to observations (for example, from the Hubble Space Telescope, the ISO satellite and new infrared and millimeter spectrographs) and partly to the advancement of hydrodynamic simulations of the structures of planetary nebulae (PN). Many of these results were reported at IAU Symposium 180 in Groningen, the Netherlands, on August 26-30th, 1996. This symposium was dedicated to one of the pioneers of PN research: Stuart Pottasch. The book contains 29 reviews and more than 200 shorter contributions.