Cosmic very high-energy gamma rays
  The article gives a brief overview, aimed at nonspecialists, about the goals and selected recent results of the detection of very-high energy gamma-rays (energies above 100 GeV) with ground based detectors. The stress is on the physics questions, especially the origin of Galactic Cosmic Rays and the emission of TeV gamma-radiation from active galaxies. Moreover some particle-physics questions which are addressed in this area are discussed. 
R. Plaga (Max-Planck-Institut fuer Physik)