The talk will consist of two parts. The first part will comprise a description of the main features of granular gases and their theoretical description. This part will include a brief description of clustering, collapse, the Maxwell demon effect, floating clusters, the question of the lack of scale separation in granular gases, the Brazil nut effect, granular hydrodynamics and (time allowing) granular boundary conditions. Should the audience be familiar with the first part, emphasis will be put on the second part, which consists of recent results, mostly on the theory of granular gases with weak frictional restitution. The latter case is an example of a system whose analysis requires the generalization of the Champman-Enskog method. Time allowing, the question of moderately dense granular gases will be briefly described. A list of some open question will conclude the talk.