The Rif package is a powerful collection of commands for the simplification and analysis of systems of polynomially nonlinear ODEs and PDEs. The package includes a command to simplify systems of ODEs and PDEs by converting these systems to a canonical form (reduced involutive form), graphical display of results for ease of use, a command to determine the initial data required for the existence of formal power series solutions of a system, and a command to generate formal power series solutions of a system.