  Following the discovery of the cosmic rays by Victor Hess in 1912, more than
70 years and numerous technological developments were needed before an
unambiguous detection of the first very-high-energy gamma-ray source in 1989
was made. Since this discovery the field on very-high-energy gamma-ray
astronomy experienced a true revolution: A second, then a third generation of
instruments were built, observing the atmospheric cascades from the ground,
either through the atmospheric Cherenkov light they comprise, or via the direct
detection of the charged particles they carry. Present arrays, 100 times more
sensitive than the pioneering experiments, have detected a large number of
astrophysical sources of various types, thus opening a new window on the
non-thermal Universe. New, even more sensitive instruments are currently being
built; these will allow us to explore further this fascinating domain. In this
article we describe the detection techniques, the history of the field and the
prospects for the future of ground-based very-high-energy gamma-ray astronomy.
