The title of “Doctor” can be a confusing one. Many types of medical training use the title “Doctor” for their graduates, including medical colleges, dental colleges and osteopathic colleges. Graduates trained in podiatry, chiropractic and naturopathy also use the title “doctor.” For most people, the title “Doctor" is associated with medicine taught at an accredited school using standardized methods. Doctors pass standardized tests to prove they have a knowledge base comparable to other doctors. By these standards, there are several types of “doctors” practicing medicine.

Medical Doctors

Medical doctors are what most people first think of when they think of medical practitioners. Medical doctors are designated by “M.D.” after their names. They attend four years of medical school after college, then undergo medical residency in a hospital setting. Most M.D.s today specialize in one area of medicine right out of medical school. Every M.D. must pass the United States Medical Licensing Examination (USMLE), which can be taken only by graduates of an accredited medical school, the U.S. Department of Labor reports.

Doctors of Osteopathy

Doctors of Osteopathy, recognized by the initials “D.O.” after their names, undergo training that is very similar to a medical doctor’s training. They go through four years of postgraduate school, followed by residency and specialization, in many cases. They also must pass the same licensing exams. Osteopathic doctors put more emphasis on the whole person and on the musculoskeletal system, using manipulation techniques not taught in medical school, according to the American Osteopathic Association.

Podiatrists

Podiatrists treat feet. Podiatrist training consists of four years of podiatric college after three to four years of college; 95 percent of podiatrists have a college degree, the Department of Labor reports. Podiatry graduates are recognized by D.P.M. (Doctor of Podiatric Medicine) after their names. Most graduates go through a two- to four-year residency program after graduation, and must pass oral and written tests to be licensed.

Chiropractors

Chiropractors can be recognized by “D.C.” (Doctor of Chiropractic) after their names. Chiropractors specialize in manipulation and alignment of bones and muscles to achieve good health. To attend chiropractic college, which lasts four years, requires two to four years of college, although more schools are now requiring college degrees. All states require passing exams for licensure.

Naturopathic Doctors

Naturopathic doctors, designated by N.D., are not legally recognized in every state. N.D.s practice holistic medicine that encompasses the use of herbs, acupuncture and massage, along with chiropractic techniques and nutrition. N.D. schooling consists of four years at a naturopathic college after undergraduate college, and the naturopath must pass a national exam to be licensed.