Beam-beam effects in electron and proton colliders

Beam-beam effects in electron and proton colliders are reviewed, with attention given to both electron-positron colliders and proton-antiproton colliders. Recent observations in existing colliders are discussed. The frequencies of the coherent oscillations of the rigid bunches coupled by the beam-beam forces in electron-positron colliders are discussed. Several attempts to understand theoretically the nature of the electron-positron collider, beam-beam interaction are described. An interpretation of the observations of the tune spreads present in the colliding beams in proton-antiproton colliders is presented and the observed distribution functions are discussed