2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/207551We review the most important topics and objectives of the physics program of the gamma-gamma, gamma-electron collider (photon collider) option for an e+e- linear collider.36 pages, Latex, 11 figures(ps,eps), Talk at Intern. Workshop on High Energy Photon Colliders; June 14-17, 2000, DESY, Hamburg, Germany; to be published in Nucl. Instr. and Methods AHigh Energy Physics - Phenomenologytext