Direct current geoelectric and low-frequency electromagnetic measurements are used for structural investigation and process monitoring. The works include small-scaled investigations of the near surface, but also the imaging of deep geological structures. The measurements are usually done at the Earth's surface, in boreholes, also between boreholes and the surface. Besides classical galvanic coupling, capacitive and inductive coupling can be used. Modern modelling and inversion algorithms are necessary, e.g. for incorporating prior information or for combination of different methods. Technical new and further development are the basis for data quality and thus for the meaningful interpretation of the results.