The National Institutes of Health (NIH) is a federal agency that conducts and supports medical research and training in the United States. The agency was founded in 1887 and is headquartered in Bethesda, Maryland. The NIH is composed of 27 institutes and centers that focus on different areas of health research, including cancer, heart disease, and infectious diseases. The agency is committed to improving the health of people in the United States and around the world through research and education.