Board-certified specialists are doctors who have advanced education, clinical training, and certification in a specific field. A subspecialist is a doctor who is trained or certified as a specialist and then receives additional training in a specific area (subspecialty).

A doctor becomes board-certified by completing training in a specialty area and passing an examination. To be board-certified, the doctor must complete the education required to get an MD (medical doctor) or DO (doctor of osteopathic medicine) degree, complete 3 to 7 years of training in a residency program in the specialty field, and pass a written test given by the specialty board. Many specialty boards also require doctors to pass an oral test.

Specialty boards certify that doctors have met certain standards. Certification is voluntary; not all specialists are certified. There are 24 specialty boards currently recognized by the American Board of Medical Specialties and the American Medical Association. Most specialties require recertification every 5 to 10 years.