The Affordable Care Act (ACA), also known as Obamacare, is a comprehensive healthcare reform law that was enacted in 2010 under President Barack Obama. The law aims to provide affordable and accessible healthcare to all Americans by expanding Medicaid coverage, establishing health insurance exchanges, prohibiting insurance companies from denying coverage due to pre-existing conditions, and requiring individuals to have health insurance or pay a penalty. The ACA also introduced a range of preventative health measures and established regulations on insurance companies to promote transparency and fairness in the healthcare system.