  The diffractive dissociation of virtual photons, gamma*p -> Xp, has been
studied in ep interactions at HERA with the H1 and ZEUS detectors. The data are
presented in terms of the diffractive structure function F2D and of the
diffractive cross sections dsigma/dt and dsigma/dMX. The t-dependence of the
cross section is measured. The Pomeron intercepts extracted from diffractive
and inclusive ep interactions are compared. The result is further interpreted
studying the dependence of the ratio between the diffractive to the inclusive
cross section on the photon-proton center of mass energy. Recent data on the Q2
dependence of the diffractive cross section at 0.17 < Q2 < 0.70 GeV2 constrain
the transition in diffraction from the perturbative high Q2 region to the
photoproduction limit.
