There are two ways to achieve the title of doctor and practice medicine:  A medical doctor (MD), or a doctor of osteopathy (DO).   In more ways than not, these two types of training complement any specialty practice.  Both trainings allow a physician to practice medicine and both have equally rigorous testing.  Both MDs and DOs begin training by getting a four-year undergraduate degree, either in pre-med, or in a related science field. Both then complete four years of training before taking examinations that will result in licensure.  Either type of doctor may then choose to specialize in a particular field and study for two to six more years. All doctors who specialize take further examinations to be licensed by that particular specialty board.