wavefunction at high energy contains many gluons which carry a small fraction x of the valence quark
energy. At fixed impact parameters as one increases the hadron
energy, the gluon occupation number in the wavefunction eventually saturates and becomes of order of
, the maximum allowed by QCD. The resulting hadron state at high energy is then called a Color Glass Condensate (CGC). Signatures and predictions of the formalism are reviewed and compared with the experimental data at RHIC.