Future Prospects of Gamma–Gamma Collider

Gamma–gamma colliders based on backward Compton scattering have been discussed mainly as an option for high energy electron–positron linear colliders, aiming to play a complementary role in energy frontier physics. The flexibility of gamma-ray beam by the Compton scheme, however, allows us to apply them to physics in a wide energy range, from MeV to TeV. In this paper, we review the future prospects of gamma–gamma colliders including recent discussions about Higgs boson factories and mid- and low-energy colliders as well as the option for electron–positron linear colliders.