Interest rate
An interest rate is the price of borrowing money, expressed as a percentage of the amount borrowed.
One price quietly governs much of the economy: the price of money over time, the interest rate.
An interest rate is the cost of borrowing money, or equivalently the reward for lending or saving it, expressed as a percentage of the amount over a period. It is one of the most important prices in any economy, because it links the present to the future and shapes nearly every financial decision.
The price of time and risk
An interest rate reflects two things: the time value of money, the fact that a sum now is worth more than the same sum later, and the risk that a loan will not be repaid. Safer borrowers and shorter terms command lower rates; riskier ones and longer terms, higher. The structure of rates across different risks and maturities carries a great deal of information about what markets expect and fear.
The lever of policy
Interest rates are the central instrument of monetary policy. By setting a key short-term rate, a central bank influences the whole structure of borrowing costs, and through them, spending, investment, and inflation. Low rates encourage borrowing and spending and discourage saving; high rates do the opposite. Because so much hinges on this single lever, central bank rate decisions are among the most scrutinised events in economic life.
Real versus nominal
A crucial distinction is between the nominal rate, the headline figure, and the real rate, the nominal rate adjusted for inflation. What matters for economic decisions is the real rate, since it measures the true cost of borrowing in terms of purchasing power. A high nominal rate can be a low real rate if inflation is higher still, which is why focusing on the nominal figure alone misleads. Borrowers and savers are affected by what the rate means after inflation, not before.
Interest rates sit at the centre of finance and macroeconomics, connecting saving and investment, present and future, policy and the real economy. Understanding them, especially the difference between their nominal appearance and their real bite, is fundamental to making sense of how money, time, and risk are priced.