Past, Present and Future of Gamma Ray Astronomy

Gamma Rays from space are created in the most violent processes in the universe and are unique probes of the high-energy universe. With the efforts of dedicated scientists it took decades from the basic insight that astronomy with gamma rays should be possible to the first detection of a source. During the last decade we witnessed a booming field with many important results. In the very near future the world wide community constructs the "Cherenkov Telescope Array" (CTA) with unprecedented performance for a significant advancement of the understanding of Supernova Remnants, Active Galactic Nuclei and many other source classes, and a huge potential for discoveries of the unexpected. This colloquium illustrates this fascinating journey.