  The properties of X-ray emission from accreting black holes are reviewed. The
contemporary observational picture and current status of theoretical
understanding of accretion and formation of X-ray radiation in the vicinity of
the compact object are equally in the focus of this chapter. The emphasis is
made primarily on common properties and trends rather than on peculiarities of
individual objects and details of particular theoretical models. The chapter
starts with discussion of the geometry of the accretion flow, spectral
components in X-ray emission and black hole spectral states. The prospects and
diagnostic potential of X-ray polarimetry are emphasized. Significant attention
is paid to the discussion of variability of X-ray emission in general and of
different spectral components -- emission of the accretion disk, Comptonized
radiation and reflected component. Correlations between spectral and timing
characteristics of X-ray emission are reviewed and discussed in the context of
theoretical models. Finally, a comparison with accreting neutron stars is made.
