  The Giant Array for Neutrino Detection (GRAND) is a proposal for a giant
observatory of ultra-high energy cosmic particles (neutrinos, cosmic rays and
gamma rays). It will be composed of twenty subarrays of 10 000 antennas each,
totaling a detection area of 200 000 km$^2$. GRAND will reach unprecedented
sensitivity to neutrinos allowing to detect cosmogenic neutrinos while its
sub-degree angular resolution will also make it possible to hunt for point
sources and possibly start neutrino astronomy. Combined with its gigantic
exposure to ultra-high energy cosmic rays and gamma rays, GRAND will be a
powerful tool to solve the century-long mistery of the nature and origin of the
particles with highest energy in the Universe. On the path to GRAND, the
GRANDProto300 experiment will be deployed in 2020 over a total area of 200
km$^2$. It primarly aims at validating the detection concept of GRAND, but also
proposes a rich science program centered on a precise and complete measurement
of the air showers initiated by cosmic rays with energies between 10$^{16.5}$
and 10$^{18}$ eV, a range where we expect to observe the transition between the
Galactic and extra-galactic origin of cosmic rays.
