The small bodies in planetary systems are indicative of the material evolution, the dynamical evolution and the presence of planets in a system. Recent astronomical research, space research, laboratory research and numerical simulations have brought a wealth of new and exciting findings on extra-solar planetary systems and on asteroids, comets, meteoroids and trans-Neptunian objects in our solar system. Progress in astronomical instrumentation has led to the discovery and investigation of small bodies in the outer solar system and to observations of debris disks related to the small bodies in extra-solar planetary systems. Space research allowed for close studies of some of the small solar system bodies from spacecraft. This class-tested lecture set is intended as an introduction to the latest research results and to the key issues of future research.