abstract: - Littlewood-Paley theory, characterization of Sobolev and Hölder spaces - Decomposition of classical symbols; boundedness in $L2$ - Oscillatory integrals - Classical pseudodifferential operators, symbolic calculus, wave front - Classes $Sm{\rho,0}$ and hypoelliptic operators of constant strength - Brief survey of the $S{\rho,\delta }$ calculus and of the Weyl-Hörmander calculus - Paraproduct, paradifferential operators, symbolic calculus - Paralinearization of nonlinear differential equations - Microlocal ellipticity - Propagation of singularities.