The Standard Industrial Classification SIC is a system for classifying industries by a four-digit code. Established in the United States in 1937, it is used by government agencies to classify industry areas. The classification was 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. The SIC system is also used by agencies in other countries. In the United States the SIC code is being supplanted by the six-digit North American Industry Classification System (NAICS code), which was released in 1997; however certain government departments and agencies, such as the U.S. Securities and Exchange Commission (SEC), still use the SIC codes.

The SIC codes can be grouped into progressively broader industry classifications: industry group, major group, and division. Each and every company will have a primary SIC code. This number indicates a company’s primary line of business. What determines a company’s primary SIC code is the code definition that generates the highest revenue for that company at a specific location in the past year. The first 3 digits of the SIC code indicate the industry group, and the first two digits indicate the major group. Each division encompasses a range of SIC codes: