The Consumer Price Index (CPI) measures the average change in prices that urban consumers pay for a basket of everyday goods and services.
CPI is published monthly by the Bureau of Labor Statistics (BLS). It tracks prices for things like food, rent, gasoline, clothing, medical care and airline fares. News reports usually quote the change over the past 12 months (the headline inflation rate) and 'core CPI', which excludes food and energy because those prices swing a lot.
Why it matters to you
CPI is the most-watched inflation number. A hotter-than-expected CPI report can move stocks, bonds and mortgage rates the same day, and it is used to adjust Social Security payments and some tax brackets.