  We give a complete description of sampling and interpolation in the
Bargmann-Fock space, based on a density concept of Beurling. Roughly speaking,
a discrete set is a set of sampling if and only if its density in every part of
the plane is strictly larger than that of the von Neumann lattice, and
similarly, a discrete set is a set of interpolation if and only if its density
in every part of the plane is strictly smaller than that of the von Neumann
lattice.
