The question of whether the United States will have functioning markets where individuals can buy health care insurance lies at the heart of the current debate about repealing and replacing the Affordable Care Act (ACA). Since about 20 million Americans depend on these markets for insurance — and thus access to health care — their functioning is also essential to the future of the U.S. health care system. To understand the ongoing battles about the individual, or non-group, markets and their reform, three points should be kept in mind.