While the next generation ee and pp colliders have been optimized for studies of the mechanism of electroweak symmetry breaking, the future ep (eA) colliders have to be designed as dedicated QCD facilities optimized for precise studies of strong interactions in their full complexity. In my talk I shall concentrate on those aspects of the future experimental research program in QCD, which, in my view, illustrate best the uniqueness of the high energy ep (eA) machines by exploiting merits of: leptons as high resolution probes of static properties of hadronic matter and ions as femto-analyzers of the dynamics of interactions of hadronic matter constituents.