[en] Recent experimental data on fusion which call for a better understanding are reviewed. A macroscopic dynamical model allowing to understand these data is described. In this approach a phenomenon intermediate between deep inelastic reactions and compound nucleus formation appear: fast fission. The conditions under which fast fission can be observed, as well as its properties are discussed. A comparison with another approach of the same problems is made: the extrapush model. Finally a simple dynamical model of fusion is reviewed which reproduces pretty well a large number of experimental fusion excitation functions