abstract: My purpose in this talk is to present some old and new generic results concerning the set of zeroes of some operators. The typical claim reads as "the critical points of some functions are non degenerate" or "the eigenvalues of some linear PDEs are simple", generically with respect to one of the parameters entering into the problem, By parameter we mean for instance the metric of the manifold or the open domain under consideration. Almost all the results have been obtained in collaboration with Anna Maria Micheletti.