  The physics related to the form factors of the energy momentum tensor spans a
wide spectrum of problems, and includes gravitational physics, hard exclusive
reactions, hadronic decays of heavy quarkonia, and the physics of exotic
hadrons described as hadroquarkonia. It also provides access to the "last
global unknown property:" the D-term. We review the physics associated with the
form factors of the energy-momentum tensor and the D-term, their
interpretations in terms of mechanical properties, their applications, and the
current experimental status.
