This book reflects the extraordinary amount of progress made in planetary nebulae research in the last thirty years. Before 1970, observations of planetary nebulae were limited to the visible region, and the oretical understanding focused on the physical processes in the ionized region. As the result of observations across the electromagnetic spectrum, we now have a much better appreciation of the richness of the planetary nebulae phenomenon. All states of matter (ionized, atomic, molecular, and solid state) are present in planetary nebulae, emitting radiation via a variety of mechanisms. More importantly, we have achieved a much better understanding of the origin and evolution of planetary nebulae (hence the title of the book).

When I was first approached by the Cambridge University Press about the possibility of writing a book on planetary nebulae, I as initially hesitant given the heavy teaching and administrative duties that I have at the University. In the end, I am glad to have done it because it offered me relief from writing reports and doing budgets as well as the opportunity to organize my own thoughts on the subject. The task of writing was made easier because of the availability of software tools: the manuscript was written in CUP LATEX, the calculations performed using MATHCAD, and many of the figures prepared using AXUM.