Britain's national debt has passed three trillion pounds. But what does that actually mean for you? Imagine the public finances as three different numbers. First, the deficit. The gap in a year when the state spends more than it receives. Second, the debt. The outstanding total built up over time. Third, the interest. The cost of financing that debt. They are connected, but they're not the same thing. Governments borrow by selling bonds called gilts. Pension funds, banks, people saving, and investors overseas can all lend money. The debt isn't a personal bill that lands on every doormat, and it doesn't all come due at once. But interest is real. Higher costs put pressure on choices about public services, tax, and investment. Debt has risen sharply since the financial crisis and the pandemic. And the UK's independent forecaster expects the interest bill to rise further, though forecasts can change. So can the country afford it? That depends on borrowing costs, growth, and what money is used for. There are choices, how we tax, spend, and invest. And those choices affect people differently. What happened the last time governments tried to bring borrowing down? Who holds the debt? How does Britain compare? Explore the evidence, understand the trade-offs, and decide what matters to you.