Thermodynamic theory of stability.- Mathematical methods in stability theory.- Some physical mechanisms of hydrodynamical instabilities.- Hydrodynamic fluctuations near the Rayleigh-Benard instability.- Some topics about the transition to turbulence.- Experimental aspects of the transition to turbulence in Rayleigh-Bénard convection.- Heat flux in convective instabilities.- Unstable flows of concentrated suspensions.- Dissipative structures and oscillations in reaction-diffusion models with or without time-delay.- Fluctuations in electromagnetic systems.- Instabilities in ecology.- Strange attractors.