EXCLUSIVE AND INCLUSIVE DIFFRACTION AT HERA

This talk describes the measurement of F₂ and inclusive and exclusive diffractive cross sections in the low-x region by HERA experiments. The abundance of diffractive reactions observed at HERA indicates the presence of perturbative multi-ladder exchanges. The exclusive diffractive vector-meson and diffractive dijet production are discussed in terms of dipole models which connect the measurement of F₂ with diffractive processes and in which multiple exchanges and saturation processes are natural. The diffractive dijets are also discussed within the diffractive parton density approach. Good description of diffractive dijets in the dipole picture and in the diffractive parton density approach indicates that these two seemingly different views on diffraction are not really distinct.