This book is based on a lecture course given at Copenhagen University in the past few years to a mixed audience of advanced undergraduates, graduate students and some senior colleagues with backgrounds in either physics or astronomy. It is intended to cover a wide range of interconnected topics including thermonuclear reactions, cosmic abundances, primordial synthesis of elements in the Big Bang, stellar evolution and nucleosynthesis. There is also a (mainly analytical) treatment of factors governing the distribution of element abundances in stars, gas clouds and galaxies and related observational data are presented.

Some of the content of the course is a concise summary of fairly standard material concerning abundance determinations in stars, cold gas and ionized nebulae, cosmology, stellar evolution and nucleosynthesis that is available in much more detail elsewhere, notably in the books cited in the reading list or in review articles; here I have attempted to concentrate on giving up-to-date information, often in graphical form, and to give the simplest possible derivations of well-known results (e.g. exponential distribution of exposures in the main s-process). The section on Chemical Evolution of Galaxies deals with a rapidly growing subject in a more distinctive way, based on work in which I and some colleagues have been engaged over the years. The problem in this field is that uncertainties arising from problems in stellar and galactic evolution are compounded.