Health care payment sources fall into several broad categories, corresponding to this guide's tabs.  The principal ones are:

• Medicare (federal program for people 65 and older and people with certified disabilities)
• Medicaid (federal/state joint program, administered primarily at the state level, for people with limited income)
• Commercial Insurance (commercial companies such as Aetna, not-for-profits such as Blue Cross/Blue Shield, HMOs, and worker's compensation)
• Self-Pay (no insurance coverage)

Payment for health care services is one of the most complex topics faced by health care practitioners, researchers, students, and management professionals.  How medical care is paid for may depend on a patient's age, income level, employment status, insurance coverage, family make-up, physical condition, type of care, venue in which care is administered, the nature of one's illnesses, geographic location, and more.

Researchers, students, and practitioners often must delve into the arcane world of health care reimbursement to answer various critical questions, such as:

• Who is likely to pay for an innovative treatment?
• Which government agencies have to approve a treatment or device before insurers will cover it?
• How can I find out which current services are covered, and by whom?
• How does the payment mechanism for my target patients affect the attractiveness of my innovative procedure or device?
• Can I find out how much is likely to be paid for a new diagnostic or treatment approach?