GLAST, the Gamma-ray Large Area Space Telescope

The GLAST gamma-ray telescope mission is scheduled for launch in 2006. It will open up the photon energy range from 30 MeV to over 300 GeV to observation. This is a follow-on to the very successful EGRET instrument of the Compton Gamma ray Observatory, which took data from 1991 to 1996, but with vastly improved technology that will result in a factor of 50 in sensitivity, and a much larger energy range. I will describe the factors that made this possible, and the current status of the NASA/DoE project. There are many exciting science topics that I will mention: study of gamma-ray bursts and other transients, which will be observed by a dedicated monitor and by the telescope; resolution of the gamma-ray sky and diffuse emission; search for evidence of dark matter; and study of AGNs, pulsars and SNRs to understand the particle acceleration mechanisms.