The photon structure from deep inelastic electron–photon scattering

The present knowledge of the structure of the photon is presented with emphasis on measurements of the photon structure obtained from deep inelastic electron–photon scattering at e+e− colliders. This review covers the leptonic and hadronic structure of quasi-real and also of highly virtual photons, based on measurements of structure functions and differential cross-sections. Future prospects of the investigation of the photon structure in view of the ongoing LEP2 programme and of a possible linear collider are addressed. The most relevant results in the context of measurements of the photon structure from photon–photon scattering at LEP and from photon–proton and electron–proton scattering at HERA are summarised.