Scott Gaudi, an astronomer at Ohio State University, delivers this Institute for Advanced Study astrophysics seminar on what gravitational microlensing reveals about the population of planets beyond our solar system. Unlike transit or radial velocity surveys, microlensing catches planets by the way their gravity bends and brightens light from a background star as it passes in front, a method sensitive to colder, more distant worlds that other techniques miss. Gaudi walks through what these surveys have found so far: the frequency of planets at different masses and orbital distances, including free floating planets unbound from any star, and how those numbers compare with predictions from planet formation theory. He addresses the statistical challenges of building a demographic picture from rare, one time microlensing events and what upcoming surveys, including space based missions, are expected to add. The talk is aimed at an audience already familiar with exoplanet science rather than newcomers, delivered in IAS's Bloomberg Lecture Hall.