  High-energy photons are a powerful probe for astrophysics and for fundamental
physics under extreme conditions. During the recent years, our knowledge of the
most violent phenomena in the Universe has impressively progressed thanks to
the advent of new detectors for high-energy gamma-rays. Observation of
gamma-rays gives an exciting view of the high-energy universe thanks to
satellite-based telescopes (AGILE, GLAST) and to ground-based detectors like
the Cherenkov telescopes (H.E.S.S. and MAGIC in particular), which recently
discovered more than 60 new very-high-energy sources. The progress achieved
with the last generation of Cherenkov telescopes is comparable to the one drawn
by EGRET with respect to the previous gamma-ray satellite detectors. This
article reviews the present status of high-energy gamma astrophysics, with
emphasis on the recent results and on the experimental developments.
