Have you ever noticed all those letters after a doctor or other medical provider’s name? MD, DO, DC, RN, PA, NP…. There are dozens, and when put together, they can spell confusion. But knowing what they mean can help you get the care you need.

Those letters are credentials, indicating the level and focus of a provider’s education. They can help you determine whether the provider is licensed to perform the medical services you need, and may help determine whether those services are covered by your insurance.

Here are some of the credentials you will see for doctors, based on education and licensing in the United States.

An MD is a Medical Doctor, who is trained and licensed to diagnose and treat us at the most complicated level. MDs practice conventional or "allopathic" medicine. They generally rely on drugs or surgeries to treat patients.

Many MDs are specialists in specific body systems, diseases or skills. Additional initials designate additional credentials. For example, "MPH" indicates a Masters level degree in public health. "FACS" indicates Fellow, American College of Surgeons. Surgeons with the FACS designation have spent extra time learning the skills needed for their surgical specialties.

A DO is a Doctor of Osteopathic Medicine. A DO credential has similar education requirements to an MD. Osteopaths differentiate themselves from MDs by their whole body, or "holistic" approach to prevention or treatment, rather than focusing on one organ or body system. They base their treatment recommendations on the theory that the human body can heal itself.

More than half of American DOs are primary care doctors in areas such as pediatrics, obstetrics, gynecology or internal medicine. They may prescribe drugs, order medical tests and do surgery.

A DC is a Doctor of Chiropractic. A DC credential requires a similar amount of education to an MD or DO, but with a different emphasis. Chiropractic focuses on manipulating the spines and nervous systems of patients, and is generally regarded as a complementary or alternative profession.

Chiropractors do not prescribe drugs or perform surgeries. Some chiropractors expand their practices to include treatments such as acupuncture or herbal remedies, which many of the more conventional MDs or DOs will not, or may not legally be allowed, to prescribe.

For a master list of doctor’s designations, check out MedHunters Directory.

Next column, we’ll review the credentials of other providers, such as RNs, PAs and NPs.