The Affordable Care Act (ACA), also known as "Obamacare," calls for the creation of state insurance exchanges to act as markets where people can compare policies and buy health insurance. Individuals may also buy directly from insurers without going through an exchange, or receive coverage as an employee benefit. As an alternative for residents of states that decline to create exchanges, the federal government will also operate a health insurance exchange. The ACA eliminates pre-existing medical conditions as a basis of insurance underwriting. The hope is that the increased size of a market where everyone must be insured (or pay a tax penalty) and no one can be denied coverage will create competition that will drive down the cost of health insurance.