The Retail Price Index (RPI) is a measure of inflation in the United Kingdom. It tracks the changes in the price of a basket of goods and services over time, helping to understand how the cost of living is changing for consumers. RPI includes various items such as food, clothing, and housing costs, providing a comprehensive view of price movements. RPI is often used for adjusting wages, pensions, and contracts to maintain purchasing power. It is one of several inflation measures, alongside the Consumer Price Index (CPI), which has a different calculation method and basket of goods.