Granular gases: dynamics and collective effects

We present a biased review of some of the most 'spectacular' effects appearing in the dynamics of granular gases where the dissipative nature of the collisions leads to a rich phenomenology, exhibiting striking differences with equilibrium gases. Among these differences, the focus here is on the illustrative examples of the 'Maxwell demon'-like experiment, modification of Fourier's law, nonequipartition of energy and non-Gaussianity of the velocity distributions. The presentation remains as non-technical as possible.