Magnetic reconnection is a basic process taking place in plasmas on Earth and in space. After a general introduction, this work focusses on magnetic reconnection in the Earth magnetosphere. Because of the interaction between the solar wind and the terrestrial magnetic field, magnetic field line merging is initiated under certain conditions, leading to various phenomena like the polar aurora or the injection of high-energetic particles influencing near-Earth satellites. The author presents a method to achieve detailed information about the reconnection process from remote satellite...