The Gamma-ray Large Area Space Telescope (GLAST) mission is scheduled for launch by NASA in 2008. The main instrument (the Large Area Telescope, LAT) is an imaging, wide field-of-view, high-energy gamma-ray telescope, covering the approximate energy range from 20 MeV to more than 300 GeV, complemented by a secondary instrument (the GLAST Burst Monitor) extending the energy measurement down to 10 keV and providing a fast trigger for Gamma-ray bursts. In this talk I will give a description of the GLAST instruments and their status. Among the numerous physics questions targeted by the mission, I will focus on the search for Dark Matter annihilation signal and briefly discuss GLASTs potential for understanding of the mysterious Gamma-ray bursts.