The neutrinoless double-beta decay is widely considered to be the easiest way to discriminate between the Dirac and the Majorana nature of neutrinos. The study of such process is being carried out with different isotopes and methods
for more than two decades, but no result is yet univocally accepted by the Physics community. One of the most developed technologies makes use of germanium crystals, in which the radioactive source and the detector coincide. A brief review will be given about the characteristics of germanium experiments, the expected signal, the past and the present experiments. A more accurate study will be dedicated to the GERDA experiment, which is presently at the beginning of its data taking
