Contents:Plasma parameters – scaling law analysis – methods for building a well-adapted modelling based – key points to verify the consistence of the description and to determine the validity domain– Studies of a MHD case, a fluid description and kinetic modelling chosen in various domains as space plasma physics, fusion plasmas, astrophysics, … . Studies on the different kinds of nonlinearity encountered in the different fields of plasma physics are also seen – in wave propagation – in wave-wave interaction – in plasma-wall interaction …