  In this paper, we present a brief overview of atom interferometry. This field
of research has developed very rapidly since 1991. Atom and light wave
interferometers present some similarities but there are very important
differences in the tools used to manipulate these two types of waves. Moreover,
the sensitivity of atomic waves and light waves to their environment is very
different. Atom interferometry has already been used for a large variety of
studies: measurements of atomic properties and of inertial effects
(accelerations and rotations), new access to some fundamental constants,
observation of quantum decoherence, etc. We review the techniques used for a
coherent manipulation of atomic waves and the main applications of atom
interferometers.
