Homotopy Equivalences of 3 Manifolds with Boundaries General theory Essential singular surfaces in some special 3 manifolds Characteristic submanifolds Singular surfaces and characteristic submanifolds Singular submanifolds and characteristic submanifolds Invariance of the characteristic submanifolds under homotopy equivalences Simple 3 manifolds Attaching homotopy equivalences Dehn twists of 3 manifolds Dehn flips of 3 manifolds Homotopy equivalences of surfaces and I bundles Geometric properties of 3 manifold groups.