NAICS and SIC codes are numerical codes assigned by the U.S. government to business establishments to identify the primary business of the establishment. The classification systems were developed to facilitate the collection, presentation, and analysis of data; and to promote uniformity and comparability in the presentation of statistical data collected by various agencies of the federal government, state agencies, and private organizations. SIC codes are four digit numbers and were used by the federal government until 1997; some private publishers still use them. NAICS codes are six digits long and have been used by federal agencies starting in 1997.