The spacetime resonance method is the name of a powerful toolbox in proving the stability or small data global wellposedness of dispersive equations. In this talk, we will first introduce several preliminaries of this method. Then we discuss the spacetime resonance set of a semilinear Schrodinger equation and estimate the oscillatory integral arising from its nonlinearity. We also explain the connection between Klainerman's vector field method and the spacetime resonance method.