Health insurance is insurance that covers the whole or a part of the risk of a person incurring medical expenses, spreading the risk over a large number of persons. By estimating the overall risk of health care and health system expenses over the risk pool, an insurer can develop a routine finance structure, such as a monthly premium or payroll tax, to provide the money to pay for the health care benefits specified in the insurance agreement. The benefit is administered by a central organization such as a government agency, private business, or not-for-profit entity.
Insurance companies are not allowed to have co-payments, caps, or deductibles, or to deny coverage to any person applying for a policy, or to charge anything other than their nationally set and published standard premiums. Therefore, every person buying insurance will pay the same price as everyone else buying the same policy, and every person will get at least the minimum level of coverage.
The Commonwealth Fund, in its annual survey, "Mirror, Mirror on the Wall", compares the performance of the health care systems in Australia, New Zealand, the United Kingdom, Germany, Canada and the U.S. Its 2007 study found that, although the U.S. system is the most expensive, it consistently under-performs compared to the other countries. One difference between the U.S. and the other countries in the study is that the U.S. is the only country without universal health insurance coverage.
Public health has been described as "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals." It is concerned with threats to the overall health of a community based on population health analysis. The population in question can be as small as a handful of people or as large as all the inhabitants of several continents (for instance, in the case of a pandemic). Public health has many sub-fields, but typically includes the interdisciplinary categories of epidemiology, biostatistics and health services. Environmental health, community health, behavioral health, and occupational health are also important areas of public health.
The compulsory insurance can be supplemented by private "complementary" insurance policies that allow for coverage of some of the treatment categories not covered by the basic insurance or to improve the standard of room and service in case of hospitalisation. This can include complementary medicine, routine dental treatment and private ward hospitalisation, which are not covered by the compulsory insurance.
Usage Note: Some people insist on maintaining a distinction between the words healthy and healthful. In this view, healthful means "conducive to good health" and is applied to things that promote health, while healthy means "possessing good health," and is applied solely to people and other organisms. Accordingly, healthy people have healthful habits. However, healthy has been used to mean "healthful" since the 1500s, as in this example from John Locke's Some Thoughts Concerning Education: "Gardening ... and working in wood, are fit and healthy recreations for a man of study or business." In fact, the word healthy is far more common than healthful when modifying words like diet, exercise, and foods, and healthy may strike many readers as more natural in many contexts. Certainly, both healthy and healthful must be considered standard in describing that which promotes health.
A contract between an insurance provider (e.g. an insurance company or a government) and an individual or his/her sponsor (e.g. an employer or a community organization). The contract can be renewable (e.g. annually, monthly) or lifelong in the case of private insurance, or be mandatory for all citizens in the case of national plans. The type and amount of health care costs that will be covered by the health insurance provider are specified in writing, in a member contract or "Evidence of Coverage" booklet for private insurance, or in a national health policy for public insurance.
In the first decade of the 21st century, the conceptualization of health as an ability opened the door for self-assessments to become the main indicators to judge the performance of efforts aimed at improving human health. It also created the opportunity for every person to feel healthy, even in the presence of multiple chronic diseases, or a terminal condition, and for the re-examination of determinants of health, away from the traditional approach that focuses on the reduction of the prevalence of diseases.