Neutrinoless double beta decay.

Neutrinoless double beta decay is a hypothesised nuclear process in which two neutrons simultaneously decay into protons with no neutrino emission. The prized observation of this decay would point to the existence of a process that violates a fundamental symmetry of the Standard Model of particle physics, and would allow to establish the nature of neutrinos. Today, the lower limits on the half-life of this process exceed $10^{25}\mbox{--}10^{26} {yrs}$. I will review the current status of the searches for double beta decay and the perspectives to enhance the experimental sensitivity in the next years.