Neutrinoless double beta decay discovery would be one of the most interesting milestones in neutrino physics. It would have implications not only in the symmetries that govern the leptons physics but also shed light on the evolution of the Universe. Specifically,this process violates the lepton number, allowing leptogenesis processes; and the Majorana nature of the neutrino which, through the see-saw mechanism, provides a mechanism to explain the low values of the neutrino mass compared with the other fermions. Additionally,in the standard scenario, with a light Majorana neutrino and without sterile ones, the neutrino-mass ordering could be determined once the half-life limit reaches 5x10**28 years.
To reach this limit in a reasonable time period, 10 years or less, ton-scale neutrinoless double beta decay detectors are needed. This talk will present an overview over the current double beta decay experiments, focusing on the experiments that search for neutrinoless double beta decay in Ge, Xe, Te and Nd, which are the isotopes with the best sensitivity.