2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/71897We prove that a birational morphism of projective 3-folds, over a field of characteristic zero, can be made toroidal by performing a sequence of blow ups of points and nonsingular curves above the domain and target.105 papes. Revision includes a new 5 page section ``An outline of the proof''. Some typos and minor corrections have been made. References have been updatedAlgebraic Geometry14E05text