Microlensing as a tool for detecting exoplanets

When a sufficiently compact massive body passes in front of a star, it focusses the light of the star towards us, according to general relativity. This leads to an increase and then to a decrease of the star's brightness (magnification) during the passage. Such microlensing events are routinely observed since the 1990s. With this method, more than hundred exoplanets have been detected by now. - In this talk I discuss the gravitational lens equation which is used for the evaluation of microlensing observations, and I review the present status of exoplanet detections and future perspectives.