[en] The QCD expectations for the behaviour of the deep inelastic scattering structure functions in the region of small values of the Bjoerken parameter x are summarized. The Balitzkij, Lipatov, Fadin, Kuraev (BFKL) equation which sums the leading powers of αln(1/x) is described and confronted with the ''conventional'' formalism based on the leading order QCD evolution equations. The small x behaviour of the spin dependent structure function g₁ is also discussed. The dedicated measurements of the hadronic final state in deep inelastic scattering at small x probing the QCD pomeron are described. This includes discussion of the deep inelastic scattering accompanied by forward jets as well as production of forward prompt photons and π⁰-s. Finally the basic facts concerning the deep inelastic diffraction are briefly summarized. (author)