The Giant Radio Array for Neutrino Detection is a proposal for a giant observatory for cosmic particles (neutrinos, ultra-high energy cosmic rays and gamma rays). The detector will be composed of 20 subarrays of 10000 antennas each, totaling a detection area of 200'000 km², detecting these particles through the radio emission associated with the air showers induced by these cosmic particle in the atmosphere.
I will detail the very ambitious science program of GRAND and the challenges that will have to be tackled before its completion, expected in the early 2030's. I will also present the GRANDProto300 experiment, a pathfinder for GRAND, which primary goal is to validate GRAND's detection principle, but also a scientific experiment of its own, with a rich science program centered on the study of cosmic rays in the 10^16.5-10^18eV energy range, where transition between galactic and extragalactic origin is expected to occur.
