Health insurance companies are not actually providing traditional insurance, which involves the pooling of risk, because the vast majority of purchasers actually do face the harms that they are "insuring" against. Instead, as Edward Beiser and Jacob Appel have separately argued, health insurers are better thought of as low-risk money managers who pocket the interest on what are really long-term healthcare savings accounts.
Over time, the operations of many Blue Cross and Blue Shield operations have become more similar to those of commercial health insurance companies. However, some Blue Cross and Blue Shield plans continue to serve as insurers of last resort. Similarly, the benefits offered by Blues plans, commercial insurers, and HMOs are converging in many respects because of market pressures. One example is the convergence of preferred provider organization (PPO) plans offered by Blues and commercial insurers and the point of service plans offered by HMOs. Historically, commercial insurers, Blue Cross and Blue Shield plans, and HMOs might be subject to different regulatory oversight in a state (e.g., the Department of Insurance for insurance companies, versus the Department of Health for HMOs). Today, it is common for commercial insurance companies to have HMOs as subsidiaries, and for HMOs to have insurers as subsidiaries (the state license for an HMO is typically different from that for an insurance company). At one time the distinctions between traditional indemnity insurance, HMOs and PPOs were very clear; today, it can be difficult to distinguish between the products offered by the various types of organization operating in the market.
Health insurance in the United States is any program that helps pay for medical expenses, whether through privately purchased insurance, social insurance, or a social welfare program funded by the government. Synonyms for this usage include "health coverage", "health care coverage", and "health benefits". In a more technical sense, the term "health insurance" is used to describe any form of insurance providing protection against the costs of medical services. This usage includes private insurance and social insurance programs such as Medicare, which pools resources and spreads the financial risk associated with major medical expenses across the entire population to protect everyone, as well as social welfare programs like Medicaid and the Children's Health Insurance Program, which both provide assistance to people who cannot afford health coverage.