This primer gives a brief glimpse of available data on health care costs, and summarizes the impact of spending growth on various parts of society.  The National Health Expenditure Accounts (NHEA), the source for several of the analyses shown, present the costs of care by type of health service or product (such as hospital care, physician services, or prescription drugs), sources of funds (such as private insurance, Medicare, Medicaid, or out-of-pocket by the individual patient), and types of sponsors (private business, households, and government).  Results from both the Kaiser Family Foundation/Health Research and Educational Trust Employer Health Benefits Survey and the Medical Expenditures Panel Survey are also shown to help explain how health costs affect families.  Finally, we conclude by discussing some commonly-held explanations for why health care costs grow over time, how they might be addressed, and the effect of the ACA. Published: 2012