• Doctors complete medical school and additional practical training.doctor image by Elena Vdovina from Fotolia.com
  
  Medical doctors work in many locations including hospitals, private practices, government agencies and research facilities. In 2008, physicians and surgeons filled over 660,000 jobs in the United States, according to the Bureau of Labor Statistics. Some specialist areas receive significantly higher pay than others, creating strong competition for residency posts. However, the United States faces a potential shortage of doctors over the next 15 years, particularly in primary care, according to the Wall Street Journal.
  
  

Primary Care

• The majority of medical doctors, over 350,000, work in primary care, according to the Wall Street Journal. Primary care doctors work with patients to prevent disease and treat disorders, manage and coordinate care and refer to specialists. Types of doctors involved in primary care include those working in family practice, internal medicine and pediatrics, according to the American Medical Association. In 2000, the top three types of primary care doctors worked in internal medicine followed by general and family practice and finally pediatrics, according to the U.S. Department of Health and Human Services.
  
  

Specialists

• Specialists include doctors who work in both primary care and other areas. In 2000, the four most actively employed medical specialist types not involved in primary care include psychiatry, anesthesiology, emergency medicine and cardiology, according to the Department of Health. Typically, specialists treat specific issues for limited time or may diagnose and refer treatment back to the primary care physician. In the United States, doctors work in over 100 specialties and subspecialties, according to the Association of American Medical Colleges.
  
  

Surgeons

• Surgeons accounted for over 150,000 active medical doctors in 2000. The top types of surgical specialists listed by the Department of Health and Human Services include obstetrics and gynecology, general surgery and orthopedic surgery. Surgeon involvement with patients may include other areas than surgery, including diagnosis, preoperative, postoperative and trauma care, according to the American Medical Association.