This simple and qualitative discussion is an attempt to include in a comprehensive framework the problem of earthquake forecasting and univocally clarify the meaning of “precursor” and the true importance of their study. It is also the starting point to present the potential of the electromagnetic precursor in the framework of classic precursors. The fact that seismic precursors are truly existing phenomena does not represent the solution to the problem of deterministic forecasting. Currently a precursor is not a prediction aid but an investigative tool of the earthquake preparation process: aka the complex mechanism of microfracturing, growth and selforganization of fractures that is necessary to produce ruptures in the crust. Scholz’s “Theory of Dilatance” (ToD), improved and further...