Britain's finances are argued about every week. The market underneath them is barely taught.

When the government spends more than it raises in tax, the gap is the deficit, and it is filled by borrowing. The stock of that borrowing still outstanding is the national debt. Almost all of the debt that matters for the weekly argument is in gilts: bonds issued by the United Kingdom, sold by the Debt Management Office, and held by pension funds, insurers, banks and overseas investors.

The other phrases are prices in the same neighbourhood. Bank Rate is the overnight interest rate set by the Bank of England. Inflation is what changes the value of a fixed payment, and what lifts the bill on index-linked gilts. A mortgage rate is a loan to a household, and a fixed-rate mortgage is priced from a point on the same curve of yields, plus the lender's margin. Talk about any one of these, and you are talking about this market, whether or not the speaker names it.

The argument is conducted by journalists, by commentators, by politicians and by the people who write policy. The general level of understanding is poor, and the reason is not a mystery. Gilts are not taught at GCSE, and they are not taught at A-level. It is possible to leave a first-class economics degree without ever having studied the government bond market: how an auction clears, what a yield actually is, who has to own the long end, and why a change in Bank Rate is not the same thing as a change in the ten-year yield.

That is a serious failure once the importance of the market is clear. It is where the government's interest bill is set. It is where pension schemes hedge the incomes they have promised. It is where a bank hedges a fixed-rate mortgage. Decisions about tax, spending and interest rates land here first, as a price, before they land anywhere else. A public argument that cannot read that price is arguing in the dark.

The aim is to show a layperson how the gilt market works. Not a dealing manual, and not a verdict on whether a politician was fair. A mechanism: the bond itself, the curve of yields, the calendar of what falls due, the auction that sets the rate the government pays, and the difference between who holds the stock and who sets the price.

Follow that through and the news starts to sort itself. A headline about "the markets" might be about Bank Rate, or about the long end, or about an auction that failed to find buyers at yesterday's yield. Those are different events. Along the way, this is a much deeper knowledge of how the country works: how it funds itself, who it owes, and what it means when the price of that debt moves.

The figures are official. Where a number people ask for is not published, the page says so.