The Affordable Care Act (ACA), formally the Patient Protection and Affordable Care Act (PPACA) and informally known as Obamacare, is a landmark U.S. federal statute enacted by the 111th United States Congress and signed into law by President Barack Obama on March 23, 2010. Together with amendments made to it by the Health Care and Education Reconciliation Act of 2010, it represents the U.S. healthcare system's most significant regulatory overhaul and expansion of coverage since the enactment of Medicare and Medicaid in 1965. Most of the act remains in effect.