The National Health Service was founded in 1948 on a single, radical principle: healthcare should be free at the point of use, funded by taxation, and available to everyone regardless of their ability to pay. Before 1948, if you couldn't afford a doctor, you didn't see one. Since 1948, treatment in the UK is free when you need it — from a broken arm to a heart transplant.
Where does the money come from?
The NHS is funded almost entirely through general taxation — income tax, National Insurance contributions, and other taxes. You don't pay directly when you use it (with a few exceptions like dental treatment and prescription charges in England). Instead, everyone who earns money pays into the system through tax, and that collective pot funds care for everyone when they need it.
The NHS is the ultimate insurance scheme. Most years, most healthy people pay in and don't need much. But when serious illness strikes — cancer, a car accident, a premature birth requiring months of intensive care — the cost of treatment could easily be hundreds of thousands of pounds, which almost nobody could afford alone. The NHS means that catastrophic illness doesn't also mean financial ruin. It is, in effect, what happens when everyone in the country insures everyone else, with the government running the scheme and no profit being extracted.
How is it structured?
The NHS in England is divided into primary care (GPs — your first point of contact for most health issues), secondary care (hospitals, specialists, surgery — you're usually referred here by your GP), and community care (district nurses, mental health services, physiotherapy). NHS Scotland, NHS Wales, and Health and Social Care in Northern Ireland operate separately, as health is a devolved responsibility, though all follow the same founding principles.
Is it free for everyone?
UK residents are entitled to NHS care. Visitors are charged for non-emergency treatment. EU citizens had reciprocal arrangements before Brexit, and international agreements cover some others. Certain services — adult dental, eye tests, prescriptions in England — are charged, though many groups (children, pensioners, pregnant women, people on low incomes) are exempt. Emergency treatment is always free to everyone, regardless of citizenship or ability to pay.