Ground-based gamma-ray astronomy, which provides access to the very-high energy (VHE; > 100 GeV) domain, has reached its maturity with the current generation of Atmospheric Cherenkov Telescopes (ACTs), such as H.E.S.S., MAGIC and VERITAS. Since the start of their operations in 2004, these experiments have increased the VHE source catalogue by almost an order of magnitude: today there are over a 100 detected TeV sources in comparison to the 15 sources which were known to that date. The new discoveries have opened up a wealth of new information on the most energetic astrophysical systems of the universe, with important consequences to our understanding of these objects. In this talk I will draw a brief introduction to the observational aspects of this emerging field of astrophysics, before presenting some of results on extragalactic TeV sources (blazars and radio galaxies) which in my opinion are amongst the most interesting. Both the introductory remarks to the field and the observational data presented will lean mostly on the results obtained by the H.E.S.S. experiment.