  Microcanonical thermodynamics (MT) is analysed for phase transitions of first
and second order in finite systems. The transiton temperature, the latent heat
and the surface tension of first order transitions can easily be determined by
MT from the caloric equation of state T(E). The outstandig problem of the
physical meaning of its backbending is clarified for the Potts-model. The
fragmentation phase transition for nuclear multifragmentation is examined in
detail. Further experimental signals of the fragmentation transition in hot
nuclei are discussed.
