  The STEREO experiment is a very short baseline reactor antineutrino
experiment aiming at testing the hypothesis of light sterile neutrinos as an
explanation of the deficit of the observed neutrino interaction rate with
respect to the predicted rate, known as the Reactor Antineutrino Anomaly. The
detector center is located 10 m away from the compact, highly $^{235}$U
enriched core of the research nuclear reactor of the Institut Laue Langevin in
Grenoble, France. This paper describes the STEREO site, the detector components
and associated shielding designed to suppress the external sources of
background which were characterized on site. It reports the performances in
terms of detector response and energy reconstruction.
