The two main tools
Interest rate policy is the primary tool. When a central bank raises its policy rate (the Bank Rate in the UK, the Federal Funds Rate in the US), it becomes more expensive for commercial banks to borrow — they pass this on through higher mortgage and loan rates, which slows borrowing, spending, and inflation. When it cuts rates, credit becomes cheaper, stimulating the economy. Quantitative easing (QE) is the secondary tool, used when policy rates reach zero: the central bank creates money and buys assets (government bonds), injecting money into the financial system to lower long-term rates further.
Independence from government
Central banks in most advanced economies are formally independent from day-to-day government control. The Bank of England was made operationally independent in 1997; the Fed has had statutory independence since 1913. The reason: governments have an incentive to print money before elections to boost growth, at the cost of inflation later. An independent central bank, with a clear inflation mandate, can resist this political pressure. This independence is considered essential for monetary credibility — but is regularly challenged. Central bank independence became highly politically contested globally from 2016 onwards.
Lender of last resort
Central banks act as the financial system’s ultimate backstop. If a commercial bank faces a liquidity crisis (short of cash despite being solvent), the central bank will lend to it — preventing panic from spreading. This function, first articulated by Walter Bagehot in 1873, is why the financial system didn’t completely collapse in 2008: the Fed, ECB, and Bank of England lent enormous sums to stricken banks. The moral hazard this creates (banks take more risks knowing they will be bailed out) is one of the fundamental tensions in financial regulation.
“The Federal Reserve’s job is to take away the punch bowl just as the party gets going.” — William McChesney Martin, Fed Chair 1951–1970
What this means for you
Central bank decisions affect you daily, even if invisibly. When the Bank of England raised rates from 0.1% to 5.25% in 2022–2023, millions of UK mortgage holders on variable or expiring fixed rates saw their monthly payments jump by hundreds of pounds. Savers, conversely, suddenly earned meaningful interest for the first time in 15 years. When you see a central bank announcement, ask: is it raising or cutting rates? Why? What does it say about the economic outlook? The answers to these questions determine the direction of mortgage rates, savings rates, the pound, and the stock market — all simultaneously.