Health services are all actions taken to protect and improve people’s health, diagnose and treat illnesses as far as possible, prevent disability and provide medical and social rehabilitation to the disabled, among others. They are one of the largest industries in most countries, consuming anywhere from 3 to 18 percent of a nation’s GDP and still growing. They employ large numbers of skilled professionals and unskilled workers, making them critical to the economic survival of many small communities.

There are a number of different types of health services available, depending on the country and the specific needs of its population. For example, some countries have universal healthcare systems that provide free or heavily subsidized medical treatment to all residents, while other countries focus on prevention and screenings in order to catch diseases early and avoid expensive treatments down the road. Still other countries prioritize specialized care for people with conditions like cancer, where early diagnosis and rapid access to the right medication can dramatically affect a patient’s prognosis.

These services can be delivered through a variety of settings, from community-based care to hospital-based care to outpatient care. In some countries, there is a three-tier hierarchical structure with primary health care providers serving as gatekeepers to higher levels of care; in other cases, the hierarchy is less structured. In either case, the delivery of health services is a complex process that depends on a multitude of factors, including the availability of healthcare facilities, funding and the organization of healthcare delivery.

In recent decades, the focus of health service research has shifted from an emphasis on the effectiveness of individual health services to a broader consideration of how the overall system of health services functions and how it might be improved. This shift is the result of a number of factors, including a proliferation of sophisticated medical technologies, changes in how health services are funded and regulated, and increased attention to the impact of healthcare on individuals’ self-rated health and overall life expectancy.

Health services research has been conducted at both the local and national level, with researchers using a wide range of tools and methodologies to study the delivery and outcomes of health services. Some examples of the most important historical work in this area include surveys sponsored by the Federal Bureau of Investigation and the predecessor to AHRQ, as well as major reports commissioned at the end of World War II that highlighted poor health standards in Britain and lack of access to healthcare services for many citizens.

The availability of healthcare services can be influenced by a variety of factors, such as financial limitations (such as the ability to afford health insurance), geographic and logistical barriers (such as distance from medical facilities or transportation costs), sociocultural expectations, and personal limitations (including a person’s health literacy, age and other factors). This is why accessibility to healthcare services is often considered a vital aspect of a country’s overall quality of life.