One of the main open issues of neutrino physics is the determination of the mass hierarchy, discriminating between the two possible ordering of the mass eigenvalues, known as Normal and Inverted Hierarchies. The solution of this puzzle would have a significant impact both on elementary particle physics and astrophysics. A possible way to investigate the problem is the study, with medium baseline reactor antineutrinos, of the mass dependent correctionsto inverse beta decays. This is the idea pursued by JUNO, a multipurpose underground liquid scintillator experiment that will start data taking in very few years from now. The main characteristics and the status of the experiment is discussed, together with its rich physics program. We focus in particular on the potentiality for mass hierarchy determination, the main goal of the experiment, oscillation parameters accurate measurements, supernova and solar neutrinos and geoneutrinos
study.