Rheumatology (Greek ρεύμα, rheuma, river) is a sub-specialty in internal medicine and pediatrics, devoted to diagnosis and therapy of rheumatic diseases. Clinicians who specialize in rheumatology are called rheumatologists. Rheumatologists deal mainly with clinical problems involving joints, soft tissues, autoimmune diseases, vasculitis, and heritable connective tissue disorders. Many of these diseases are now known to be disorders of the immune system, and rheumatology is increasingly the study of immunology. One of the major changes in modern rheumatology is the development of new drugs called biologics, or disease modifying agents, which can control severe disease more effectively.