Abstract: Dark matter is the dominating component of our universe; however, the nature of dark matter remains unknown. There exist many candidate constituents from particle physics which give very different predictions of the formation of small scale cosmic structures, so in principle we can distinguish the nature of dark matter through astronomical observations. In this article we first review the impact of different dark matter modes on cosmic structure formation, and then describe some apparent problems in the current standard cold dark matter model. Finally, we discuss recent progress in using astronomy to distinguish between cold and warm dark matter .