N ov 2 00 0 1 Diffraction in hadron-hadron interactions

Results on soft and hard diffraction in pp and ¯ pp collisions are reviewed with emphasis on factorization and scaling properties of differential cross sections. While conventional factorization breaks down at high energies, a scaling behavior emerges, which leads to a universal description of diffractive processes in terms of a (re)normalized rapidity gap probability distribution.