The Producer Price Index (PPI) is a measure of the average change over time in the selling prices received by domestic producers for their output. It is a family of indexes that measures price change from the perspective of the seller, in contrast to measures such as the Consumer Price Index (CPI), which measure price change from the purchaser's perspective. The PPI is compiled from thousands of indexes measuring producer prices by industry and product category and is published monthly by the U.S. Bureau of Labor Statistics. It is used to forecast inflation, calculate escalator clauses in private contracts, track price changes by industry, and compare wholesale and retail price trends