Inflation is defined as a persistent rise in prices over time rather than a single increase in the price level. It is measured by calculating the percentage change in a price index from one period to the next. India measures inflation using several indices, with the Wholesale Price Index (WPI) historically being the main measure and the Consumer Price Index (CPI) now being the primary target of the Reserve Bank of India's inflation targeting. The CPI is further broken down by location (rural, urban, combined), consumer category (industrial workers, agricultural laborers), and type (headline inflation includes volatile food and fuel prices, while core inflation excludes them).