  We provide a review of both new experimental and theoretical developments in
the Casimir effect. The Casimir effect results from the alteration by the
boundaries of the zero-point electromagnetic energy. Unique to the Casimir
force is its strong dependence on shape, switching from attractive to repulsive
as function of the size, geometry and topology of the boundary. Thus the
Casimir force is a direct manifestation of the boundary dependence of quantum
vacuum.
  We discuss in depth the general structure of the infinities in the field
theory which are removed by a combination of zeta-functional regularization and
heat kernel expansion. Different representations for the regularized vacuum
energy are given. The Casimir energies and forces in a number of configurations
of interest to applications are calculated. We stress the development of the
Casimir force for real media including effects of nonzero temperature, finite
conductivity of the boundary metal and surface roughness. Also the combined
effect of these important factors is investigated in detail on the basis of
condensed matter physics and quantum field theory at nonzero temperature.
  The experiments on measuring the Casimir force are also reviewed, starting
first with the older measurements and finishing with a detailed presentation of
modern precision experiments. The latter are accurately compared with the
theoretical results for real media.
  At the end of the review we provide the most recent constraints on the
corrections to Newtonian gravitational law and other hypothetical long-range
interactions at submillimeter range obtained from the Casimir force
measurements.
