Mmg is an open source software for simplicial remeshing. It provides 3 applications and 4 libraries: - the mmg2d application and the libmmg2d library: adaptation and optimization of a two-dimensional triangulation and generation of a triangulation from a set of points or from given boundary edges; - the mmgs application and the libmmgs library: adaptation and optimization of a surface triangulation and isovalue discretization; - the mmg3d application and the libmmg3d library: adaptation and optimization of a tetrahedral mesh and implicit domain meshing; - the libmmg library gathering the libmmg2d, libmmgs and libmmg3d libraries.