Health care systems are designed to meet the health care needs of target populations. There are a wide variety of health care systems around the world. In some countries, the health care system planning is distributed among market participants, whereas in others planning is made more centrally among governments, trade unions, charities, religious, or other co-ordinated bodies to deliver planned health care services targeted to the populations they serve. However, health care planning has often been evolutionary rather than revolutionary. The goals for health systems, according to the World Health Report 2000 - Health systems: improving performance (WHO, 2000), are good health, responsiveness to the expectations of the population, and fair financial contribution. Duckett (2004) proposed a two dimensional approach to evaluation of health care systems: quality, efficiency and acceptability on one dimension and equity on another.

Health care providers are trained professional people working self-employed or as an employee in an organization, whether a for-profit company, a not-for profit company, a government entity, or a charity. Organizations employing people providing health care are also known as health care providers. Examples are doctors and nurses, paramedics, dentists, medical laboratory staff, specialist therapists, psychologists, pharmacists, chiropractors, and optometrists. Health informatics or medical informatics is the intersection of information science, medicine and health care. It deals with the resources, devices and methods required to optimize the acquisition, storage, retrieval and use of information in health and biomedicine. Health informatics tools include not only computers but also clinical guidelines, formal medical terminologies, and information and communication systems. Public health 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 is typically divided into epidemiology, biostatistics and health services. Environmental, social, behavioral, and occupational health are also important subfields.

A child being immunized against polio.

Vaccination policy refers to the policy a government adopts in relation to vaccination. Vaccinations are voluntary in some countries and mandatory in some countries. Some governments pay all or part of the costs of vaccinations for vaccines in a national vaccination schedule.

Today, most governments recognize the importance of public health programs in reducing the incidence of disease, disability, and the effects of aging, although public health generally receives significantly less government funding compared with medicine. In recent years, public health programs providing vaccinations have made incredible strides in promoting health, including the eradication of smallpox, a disease that plagued humanity for thousands of years.

An important public health issue facing the world currently is HIV/AIDS. Another major public health concern is diabetes. In 2006, according to the World Health Organization, at least 171 million people worldwide.