Saturation in High Energy Scattering and Heavy Ion Collisions

Deeply inelastic lepton-hadron scattering can be viewed either as a counting of partons in the hadron or in terms of a partonic dipole scattering on the hadron. These are dual descriptions. Unitarity limits on dipole-hadron scattering correspond to maximum quark and gluon occupancy (saturation) of quarks and gluons in the hadron wave function. Examples will be discussed as well as current activity aimed at definitively seeing saturation experimentally