COMSOL Multiphysics (formerly FEMLAB) is a finite element analysis and solver software package for various physics and engineering applications, especially coupled phenomena--multiphysics. COMSOL Multiphysics also offers a smooth interface to MATLAB and its toolboxes for a large variety of programming, preprocessing and postprocessing possibilities. A similar interface is offered to COMSOL Script. The packages are cross-platform (Windows, Mac, Linux, Unix.) In addition to conventional physics-based user-interfaces, COMSOL Multiphysics also allows for entering coupled systems of partial differential equations (PDEs).