This work deals with some of the most typical complexes of interstellar matter and is intended to serve both as a reference book for the specialist and as an introduction for the newcomer to the field. It is hoped to meet the first aim by presenting a holistic view of the well studied complexes in Orion, built on information derived from various branches of modern Astrophysics. The wealth of published data is presented in the form of photographs, contour maps, diagrams and numerous heavily annotated tables. The second aim is pursued by providing an outline of the complexes, the physical...