I give a brief review of the history of photon-photon physics and a survey of its potential at future electron-positron colliders. Exclusive hadron production processes in photon-photon and electron-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes. There are also important high energy {gamma}{gamma} and e{gamma} tests of quantum chromodynamics, including the production of jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Since photons couple directly to all fundamental fields carrying the electromagnetic current including leptons, quarks, W's and supersymmetric particles, high energy {gamma}{gamma} collisions will provide a comprehensive laboratory for Higgs production and exploring virtually every aspect of the Standard Model and its extensions. High energy back-scattered laser beams will thus greatly extend the range of physics of the International Linear Collider.

The proceedings blend current and future two-photon physics. Developments since the last Photon-Photon Workshop four years ago are summarized, and the future of the field is projected, not only at existing accelerators, but also at heavy-ion colliders B-factories, and especially linear colliders with back-scattered laser beams.

This volume reports on all aspects of high energy photon interactions using both photon and proton targets. Significant new results from the LEP and HERA experiments as well as from CLEO II and BELLE are presented. These data are confronted with diverse theoretical models. In particular, predictions of QCD in both the perturbative and the non-perturbative sector are extensively discussed. The prospects for gamma-gamma physics at future high energy colliders are also reviewed. In total 72 papers are collected.The proceedings have been selected for coverage in: ? Index to Scientific & Technical Proceedings (ISTP CDROM version / ISI Proceedings)

This volume reports on all aspects of high energy photon interactions using both photon and proton targets. Significant new results from the LEP and HERA experiments as well as from CLEO II and BELLE are presented. These data are confronted with diverse theoretical models. In particular, predictions of QCD in both the perturbative and the non-perturbative sector are extensively discussed. The prospects for gamma-gamma physics at future high energy colliders are also reviewed. In total 72 papers are collected.The proceedings have been selected for coverage in:• Index to Scientific & Technical Proceedings (ISTP CDROM version / ISI Proceedings)