Comets: Relics of the early solar system

Abstract
This article gives a concise overview of the main principles and descriptions presently relevant in cometary research. As such it summarizes basic topics without going into too many details. After an historical overview and a short discussion of the scientific significance of cometary research, an outline is given on the orbital characteristics and physical properties of comets. Then the observational techniques used in cometary science are sketched out. The last section briefly addresses the diversity of comets. A comprehensive list of references is provided to allow further elaboration on the individual themes. It is meant as an introduction to the subject.