High Energy Astrophysics is one of the hottest topics in astrophysics & astronomy. It studies processes in objects that release very energetic radiation(e.g. X-ray, gamma). The goal is to understand the very structure of matter, the development of stars, and the fate of the universe itself. The book is based on a tested lecture and has a focus on experiments and observations. A modular structure allows to adaptit to individual courses' needs.