Rheumatology is a subspecialty of internal medicine dealing with diseases of joints, muscles, bones, and tendons. Rheumatic diseases encompass more than 100 discrete disorders, some with multisystem involvement, and many with a wide variety of clinical manifestations and outcomes. The disease, known colloquially as rheumatism, is the pain experienced in the joints and muscles and the ligaments connecting them. These pains can sometimes cause swelling and disfigurement. Rheumatic diseases can be classified as inflammatory and non-inflammatory.