  The Jiangmen Underground Neutrino Observatory (JUNO) is a large and high
precision liquid scintillator detector under construction in the south of
China. With its 20 kt target mass, it aims to achieve an unprecedented 3%
energy resolution at 1 MeV. Its main goal is to study the disappearance of
reactor antineutrino to determine the neutrino mass ordering, and to precisely
measure the mixing parameters $\theta_{12}$, $\Delta m^2_{12}$, and $\Delta m
^2_{ee}$. It also aims to detect neutrinos emitted from radioactive processes
taking place within the inner layers of the Earth (geoneutrinos), as well as
neutrinos produced during rare supernova bursts. Neutrinos emitted in solar
nuclear reactions could also be observed, if stringent radiopurity requirements
on the scintillator are met. This manuscript provides some highlights of JUNO's
Physics Programme, and describes the detector design, as well as the ongoing
detector R&D.
