The 'shopping basket' of items making up the Consumer Prices Index (CPI) and Retail Prices Index (RPI) are reviewed every year. Some items are taken out of the basket, some are brought in, to reflect changes in the market and to make sure the CPI and RPI are up to date and representative of consumer spending patterns. This article describes the review process and explains how and why the various items in the CPI and RPI baskets are chosen.