  The QCD expectations for the behaviour of the deep inelastic scattering
structure functions in the region of small values of the Bjorken parameter $x$
are summarized. The Balitzkij, Lipatov, Fadin, Kuraev (BFKL) equation which
sums the leading powers of $\alpha_s ln(1/x)$ 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
$g_1$ 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
$\pi^0$-s. Finally the basic facts concerning the deep inelastic diffraction
are briefly summarized.
