  The High Energy Stereoscopic System H.E.S.S. is an array of Cherenkov
Telescopes located in the Khomas Highlands in Namibia. H.E.S.S. started
operations in 2003 and has been operated very successfully since then. With its
location in the Southern hemisphere, the system provides a privileged view of
the Milky Way and the Galactic center region. With H.E.S.S., a large variety of
new TeV emitters has been discovered, both in our Galaxy and in extragalactic
space. We provide a description of the individual telescopes and of the system
as a whole, and review the scientific highlights that have been achieved with
the instrument.
