[en] The PLASMA FOCUS is created by an electrical discharge in gas at pressure in the torr range. The special singularity of the experiment occurs when the current sheath gathers radially on axis and its resistance becomes very high, around 0,2-0,4 Ω. The resistive phase creates a high voltage in the plasma column. In the following phase the current is carried by high power electron and ion beams which interact with the anode and the fill gas, respectively, and produce x-ray and neutron bursts, when deuterium is used. General rules for the operation and extrapolation to higher energies have been understood and applications have been developed. However, the structure of the current sheath and the nature of microinstabilities which are prevalent are still difficult to analyse and request large and coordinated research efforts, for which an International Centre has been recently established in Poland. (author)