  Gravity warps space and time into a funnel and generates a black hole when a
cosmic body undergoes a catastrophic collapse. What can one say about the
interior of a black hole? The important point is that inside a black hole the
space radial direction becomes time, and time becomes a space direction. The
path into the gravitational abyss of the interior of a black hole is a
progression in time. There is a peculiar region inside a black hole where some
characteristics of the space-time curvature become singular. We call this
region singularity. The colossal tidal gravitational forces near singularity
modify physical laws. Space and time are not only strongly curved near the
singularity, but they split into quanta. The fall into the singularity is
unstoppable for a body inside a black hole. This paper also addresses the
following questions:
  Can one see what happens inside a black hole?
  Can a falling observer cross the singularity without being crushed?
  Can new baby universes arise inside a black hole?
  An answer to all these questions is probably ``yes''. We give also a brief
review of the modern black hole astrophysics.
