The Patient Protection and Affordable Care Act, or ACA (sometimes colloquially referred to as Obamacare), is a major healthcare reform law passed in 2010 by Barack Obama, aimed at providing more comprehensive health insurance options for Americans. Prior to its passage, there were almost 50 million uninsured Americans, 91% of whom were earning less than 400% of the Federal Poverty Line (FPL), and many individuals were denied on the basis of their pre-existing conditions. 

The ACA was designed to increase the availability of affordable insurance options, which it did through two main mechanisms: the expansion of Medicaid and the creation of healthcare marketplaces (exchanges) where individuals could purchase insurance. It also enacted many other smaller measures, both pertaining to and separate from insurance coverage goals (e.g. authorizing the FDA to approve biosimilars, the analogue of a small-molecule generic for biologic drugs). Additionally, it ensured many patient protections and prevented insurers from denying coverage, charging higher premiums, or excluding benefits to individuals with pre-existing conditions who wished to purchase insurance. 

Notably, the ACA was intended to build on top of existing infrastructure; because of this, the many complexities of U.S. healthcare were retained, and in many cases amplified. With the expiration of subsidy rates set by the American Rescue Plan Act and the Inflation Reduction Act, it is ever more important to understand exactly where the ACA stands, and where it is headed. This article aims to break down the evolution and operation of structures established by the ACA.