  The Cesam code is a consistent set of programs and routines which perform
calculations of 1D quasi-hydrostatic stellar evolution including microscopic
diffusion of chemical species and diffusion of angular momentum. The solution
of the quasi-static equilibrium is performed by a collocation method based on
piecewise polynomials approximations projected on a B-spline basis; that allows
stable and robust calculations, and the exact restitution of the solution, not
only at grid points, even for the discontinuous variables. Other advantages are
the monitoring by only one parameter of the accuracy and its improvement by
super-convergence. An automatic mesh refinement has been designed for adjusting
the localisations of grid points according to the changes of unknowns. For
standard models, the evolution of the chemical composition is solved by stiffly
stable schemes of orders up to four; in the convection zones mixing and
evolution of chemical are simultaneous. The solution of the diffusion equation
employs the Galerkin finite elements scheme; the mixing of chemicals is then
performed by a strong turbulent diffusion. A precise restoration of the
atmosphere is allowed for.
