The CPI is the most widely used measure of inflation. The report is released at 8:30 am EST around the 15th of each month and reflects the previous month's data. The CPI measures the change in the cost of a bundle of consumer goods and services. The bundle includes about 200 types of goods and thousands of actual products, ranging from foods and energy to expensive consumer goods. The prices are measured by taking a sample of prices at different stores. In addition to the overall CPI number, it is important to also look at the "core rate." The core rate excludes volatile goods like food and energy and gives a closer measure of real inflation. Most reports of the CPI numbers will include both the overall and the core numbers. The CPI is also important because it is used to adjust the annual changes to Social Security payments. There has been much debate about how well the CPI measures inflation, and some feel that it is an imperfect way to track rising prices. To see the latest report, visit the Bureau of Labor Statistics.