IXPE, the Imaging X-ray Polarimetry Explorer, has been selected by NASA as the next mission in the Small Explorer Program, for a launch in early 2021. IXPE, a collaboration between NASA and ASI (the Italian Space Agency), will reopen, after a gap of more than 40 years, the X-ray polarimetric observing window. In this seminar, the main characteristics of the mission and its scientific objectives will be described. While at present only one positive measurement, dating back to the 70s, is available (the Crab Nebula), IXPE will provide sensitive measurements on at least the brightest objects of all major classes of X-ray sources.