HealthCare.gov is a health insurance exchange website operated by the United States federal government under the provisions of the Affordable Care Act or ACA, commonly referred to as "Obamacare", which currently serves the residents of the U.S. states which have opted not to create their own state exchanges. The exchange facilitates the sale of private health insurance plans to residents of the United States and offers subsidies to those who earn between one and four times the federal poverty line, but not to those earning less than the federal poverty line. The website also assists those persons who are eligible to sign up for Medicaid, and has a separate marketplace for small businesses.

In the United States, health insurance marketplaces, also called health exchanges, are organizations in each state through which people can purchase health insurance. People can purchase health insurance that complies with the Patient Protection and Affordable Care Act at ACA health exchanges, where they can choose from a range of government-regulated and standardized health care plans offered by the insurers participating in the exchange.