Kaiser Family Foundation offers a brief on the implementation of the Affordable Care Act

One component of the Affordable Care Act is to increase access to health insurance by expanding eligibility for Medicaid benefits. The Medicaid program provides health insurance coverage to people with low incomes and is funded jointly by the federal and state governments.  This report offers a clear explanation of the act in terms of Medicaid expansion.

http://www.kff.org/healthreform/upload/8332.pdf