The Patient Protection and Affordable Care Act, also known as the Affordable Care Act (ACA) or Obamacare, is a United States federal statute that was signed into law by the US Congress on 23 March 2010, during the presidency of Barack Obama. The ACA was the US healthcare system's most significant regulatory overhaul and expansion of coverage since the passage of Medicare and Medicaid in the Social Security Amendments of 1965.

The ACA's goal was to reduce the number of uninsured Americans, covering an additional 24,000,000 people by 2016. The act also decreased the budget deficit and slowed increases in overall healthcare spending. However, state governments, conservative advocacy groups, labor unions, and small business opposed Obamacare, claiming that the government was taking money out of the pockets of its citizens to pay for other people's healthcare; Tea Party movement opponents of the act branded it as a socialist bill and used it to attack Obama. On 20 March 2017, the American Health Care Act of 2017 was introduced by Donald Trump's faction of the Republican Party with the goal of "repealing and replacing" Obamacare, and the bill was passed on 4 May 2017 by a narrow margin of 217 to 213, although it had to be amended as the Better Care Reconciliation Act of 2017.