This volume of the Conceptual Design Report is dedicated to an overview of the FCC physics potential. It focuses on the most significant targets of the potential FCC research programme but, for the sake of space, not covering a large body of science that will nevertheless be accessible (and which is documented in various other reports, listed in the Appendix). The studies presented here, in addition to setting plausible targets for the FCC achievements, have helped in making the choice of the colliders’ parameters (energy, luminosity) and their operation plans. Furthermore, these studies contributed to the deinition of the critical detector features and parameters, as described in Volumes 2 and 3 of the CDR. While at first discussing the ta...