Health systems, explained in plain language

Healthcare treats people when they are unwell. But much of what shapes health across a population happens outside clinics and hospitals: the home people live in, the school system they went through, the income their household has, and the services available in their area. These are called social determinants of health — the conditions in which people are born, grow, live, work and age.

Economic stability — money

Income shapes what a household can afford: housing, food, transport and services. At population level, lower-income groups face more barriers to those resources.

Education access and quality — school

Education is linked at population level to literacy, employment patterns, and how easily people can find and use information and services.

Health care access and quality — services

Whether services exist nearby, whether people can reach them, and whether they are affordable shapes population health patterns.

Neighbourhood and built environment — home and place

Housing stability, crowding, transport, green space and environmental quality differ by place, and population health patterns vary with them.

Social and community context — community

Social support, discrimination and community ties shape health across groups, not only for individuals.

Read the full guide: What are social determinants of health?

Equity vs equality

Equality means giving everyone the same thing. Equity means giving people what they need to reach the same opportunity for health. Health equity is the opportunity for everyone to attain their full health potential, whatever their background.

The social gradient

Health follows income and education in every country: the lower a group’s socioeconomic position, the poorer its health on average. This pattern — the social gradient — appears in rich and poor countries alike, and it is why public health looks upstream at living conditions, not only at hospitals.

Read the full guide: What is health equity?

Clean water, sanitation and hygiene are systems, not only personal habits.

The gaps, in numbers

The WHO/UNICEF Joint Monitoring Programme reports that 2.1 billion people still lack safely managed drinking water and 3.4 billion lack safely managed sanitation (2025 report, data 2000–2024). Try the Water, Sanitation and Hygiene Tool — a general timer and quiz — or the Five Keys to Safer Food Checklist.

Health literacy is the ability to find, understand and use health information.

Two sides

It has two sides: personal health literacy (what a reader can do) and organisational health literacy (how clearly services explain things). Read the full guide: What is health literacy? Test general health literacy with the Myth or Fact Quiz, and read What is stigma? in the sibling hub Mental Health and Wellbeing.

Primary health care

Primary health care is the first level of contact people have with a health system, and the approach that organises health around communities rather than hospitals: primary care and essential public health functions, action across sectors, and empowered communities. Read the full guide: What is primary health care?

Commercial determinants of health

Commercial determinants of health are the private-sector activities that affect people’s health, positively or negatively — the industries and practices behind them, and what public health can do. Read the full guide: Commercial determinants of health, and the guide on social determinants of health for the wider picture they sit inside.

Health promotion

Health promotion is the process of enabling people to increase control over, and to improve, their health — the Ottawa Charter definition of 1986, with five action areas that work through policy, environments, communities and services as well as personal skills. Read the full guide: What is health promotion?