A specialty is the branch of medicine in which a doctor has completed advanced clinical training and education. Most doctors are board certified in their specialty. To receive the best health care for your needs, consider choosing a doctor who specializes in your particular medical condition. A specialist will concentrate on your specific needs and will be familiar with the best methods of treatment. Examples of specialists are a pediatrician who focuses on the physical, emotional, and social health of children from birth to young adulthood or a cardiologist who specializes in diseases and conditions of the heart and blood vessels. A doctor may have more than one specialty, along with one or more sub specialties. For instance, a doctor could specialize in internal medicine and have a sub specialty in infectious disease. A sub specialty is a concentration within a specialty. Your primary care doctor who is often a specialist in family medicine or internal medicine can help you choose the right type of specialist. In fact, some health insurance plans require a referral from your primary care doctor before you visit a specialist.