The electric solar wind sail (E-sail) is a newly invented method for using the solar wind dynamic pressure for producing propulsion for spacecraft. The E-sail consists of a set of long, thin, conducting and centrifugally stretched tethers which are kept positively charged by continuously operating an onboard solar-powered electron gun. The thrust effect is based on Coulombic drag that the moving solar wind exerts on the tethers and its magnitude per length is around 500 nN/m. Using today’s materials and technologies, an E-sail producing 1 N of thrust and weighing about 100 kg should be possible, and not too difficult, to build. This system would beat currently used space propulsion techniques (chemical rockets and ion engines) by 2 or 3 orders of magnitude if the lifetime-integrated total impulse per system mass is used as the figure of merit. A simple test mission ESTCube-1 (planned launch 2012) is under construction for measuring the electric sail effect in orbit for the first time. This lecture gives a summary of the present status of the physics and technology of the electric sail and its potential applications in a large variety of solar system missions.