The National Institutes of Health (NIH) is a part of the U.S. Department of Health and Human Services. It is the nation's medical research agency, responsible for studying various health issues and diseases. The NIH conducts its own research and also provides funding to researchers across the country to help advance medical knowledge and improve public health. With a focus on improving health for all, the NIH supports research on a wide range of topics, including cancer, heart disease, and mental health. By investing in scientific studies, the NIH aims to discover new treatments and enhance our understanding of how to prevent and manage illnesses.