There has recently been a renewal of interest in Fokker-Planck
operators, motivated by problems in statistical physics, in kinetic
equations, and differential geometry. Compared to more standard problems
in the spectral theory of partial differential operators, those
operators are not self-adjoint and only hypoelliptic. The aim of the
analysis is to give, as generally as possible, an accurate qualitative
and quantitative description of the exponential return to the
thermodynamical equilibrium. While exploring and improving recent
results in this direction, this volume proposes a review of known
techniques on: the hypoellipticity of polynomial of vector fields and
its global counterpart, the global Weyl-Hörmander pseudo-differential
calculus, the spectral theory of non-self-adjoint operators, the
semi-classical analysis of Schrödinger-type operators, the Witten
complexes, and the Morse inequalities.