  The review is a brief description of the state of problems in percolation
theory and their numerous applications, which are analyzed on base of
interesting papers published in the last 15-20 years. At the submitted papers
are studied both the cluster system of the physical body and its impact on the
object in general, and adequate mathematical tools for description of critical
phenomena too. Of special interest are the data, first, the point of phase
transition of certain of percolation system is not really a point, but it is a
critical interval, and second, in vicinity of percolation threshold observed
many different infinite clusters instead of one infinite cluster that appears
in traditional consideration.
