The United States Consumer Price Index (CPI) is a family of various consumer price indices published monthly by the United States Bureau of Labor Statistics (BLS). The most commonly used indices are the CPI-U and the CPI-W, though many alternative versions exist for different uses. For example, the CPI-U is the most popularly cited measure of consumer inflation in the United States, while the CPI-W is used to index Social Security benefit payments. The CPI is not the only measure of prices, with a related component being the Personal consumption expenditures price index (PCI) price index, which measures a more broad set of goods and services, among other differences.