The Imaging X-ray Polarimetry Explorer (IXPE).

X-ray polarimetry is a long-standing missing piece in the puzzle of multiwavelenght study of high energy sources. The Imaging X-ray Polarimetry Explorer (IXPE) will fill this gap in our knowedge by adding polarization measurements to observables currently avaiable: energy, time, and position. IXPE, first proposed in response of an Announcement of Opportunity issued on 2014, was selected in the context of the NASA Astrophysics Small Explorer (SMEX) program in January 2017, and is a collaboration with the Italian Space Agency (ASI). Thanks to its Gas Pixel Detector imaging-capable polarimeter, IXPE will open new a new window in the understanding of particle acceleration processes, higly magnetized compact objects and the properties of scat- tering induced polarization. Here, the thecnical aspects of the mission and some of the scientific cases that IXPE will explore will be highlighted. Special attenton will be given to a selection of extended sources that IXPE will be able to study thanks its imaging capabilities.