The Centers for Medicare & Medicaid Services (CMS) is a federal agency within the U.S. Department of Health and Human Services. It oversees the nation's major healthcare programs, including Medicare, which provides health coverage for seniors and certain disabled individuals, and Medicaid, which offers assistance to low-income individuals and families. CMS plays a crucial role in setting healthcare policies, managing funding, and ensuring quality care. The agency also works to improve healthcare access and affordability, while promoting innovation in healthcare delivery and payment systems across the United States.