Health equity arises from access to the social determinants of health, specifically from wealth, power and prestige. Individuals who have consistently been deprived of these three determinants are significantly disadvantaged from health inequities, and face worse health outcomes than those who are able to access certain resources. It is not equity to simply provide every individual with the same resources; that would be equality. In order to achieve health equity, resources must be allocated based on an individual need-based principle.

According to the World Health Organization, "Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity". The quality of health and how health is distributed among economic and social status in a society can provide insight into the level of development within that society. Health is a basic human right and human need, and all human rights are interconnected. Thus, health must be discussed along with all other basic human rights.

Health equity is defined by the CDC as "the state in which everyone has a fair and just opportunity to attain their highest level of health". It is closely associated with the social justice movement, with good health considered a fundamental human right. These inequities may include differences in the "presence of disease, health outcomes, or access to health care" between populations with a different race, ethnicity, gender, sexual orientation, disability, or socioeconomic status.

Health inequity differs from health inequality in that the latter term is used in a number of countries to refer to those instances whereby the health of two demographic groups (not necessarily ethnic or racial groups) differs despite similar access to health care services. It can be further described as differences in health that are avoidable, unfair, and unjust, and cannot be explained by natural causes, such as biology, or differences in choice. Thus, if one population dies younger than another because of genetic differences, which is a non-remediable/controllable factor, the situation would be classified as a health inequality. Conversely, if a population has a lower life expectancy due to lack of access to medications, the situation would be classified as a health inequity. These inequities may include differences in the "presence of disease, health outcomes, or access to health care". Although, it is important to recognize the difference in health equity and equality, as having equality in health is essential to begin achieving health equity. The importance of equitable access to healthcare has been cited as crucial to achieving many of the Millennium Development Goals.

Socioeconomic status is both a strong predictor of health, and a key factor underlying health inequities across populations. Poor socioeconomic status has the capacity to profoundly limit the capabilities of an individual or population, manifesting itself through deficiencies in both financial and social capital. It is clear how a lack of financial capital can compromise the capacity to maintain good health. Income is an important determinant of access to healthcare resources. Because one's job or career is a primary conduit for both financial and social capital, work is an important, yet underrepresented, factor in health inequities research and prevention efforts. There are many ways that a job can affect one's health, such as the job's physical demands, exposure to hazards, mechanisms of employment, compensation and benefits, and availability of health and safety programs. In addition, those who are in steady jobs are less likely to face poverty and its implications and more likely to have access to health care. Maintenance of good health through the utilization of proper healthcare resources can be quite costly and therefore unaffordable to certain populations.

In China, for instance, the collapse of the Cooperative Medical System left many of the rural poor uninsured and unable to access the resources necessary to maintain good health. Increases in the cost of medical treatment made healthcare increasingly unaffordable for these populations. This issue was further perpetuated by the rising income inequality in the Chinese population. Poor Chinese were often unable to undergo necessary hospitalization and failed to complete treatment regimens, resulting in poorer health outcomes.

Similarly, in Tanzania, it was demonstrated that wealthier families were far more likely to bring their children to a healthcare provider: a significant step towards stronger healthcare. Unequal income distribution itself can be a cause of poorer health for a society as a result of "underinvestment in social goods, such as public education and health care; disruption of social cohesion and the erosion of social capital".

The role of socioeconomic status in health equity extends beyond simple monetary restrictions on an individual's purchasing power. In fact, social capital plays a significant role in the health of individuals and their communities. It has been shown that those who are better connected to the resources provided by the individuals and communities around them (those with more social capital) live longer lives. The segregation of communities on the basis of income occurs in nations worldwide and has a significant impact on quality of health as a result of a decrease in social capital for those trapped in poor neighborhoods. Social interventions, which seek to improve healthcare by enhancing the social resources of a community, are therefore an effective component of campaigns to improve a community's health.