Interest is usually expressed at an annual rate: the amount of interest that would be paid during a year divided by the amount of money loaned. Developed economies offer many different interest rates, reflecting the length of the loan and the riskiness and wealth of the borrower. People often use the term “interest rate” when they mean the short-term interest rate charged to banks. For instance, when a central bank raises or cuts interest rates, it changes only the price it charges to banks borrowing money overnight, expressed as an annual rate. Bond yields are a better measure of the interest rate on loans that do not have to be repaid for many years. Unlike short-term interest rates, bond yields are determined not by central bankers but by the supply and demand for money, which is heavily influenced by the expected rate of inflation.