Standard Industrial Classification (SIC) used to be a system for classifying industries for government-related and statistics-related classifying purposes. It uses a 4-digit code, called SIC code. It was first established in 1937 in the United States. The SIC system is also used by agencies in other countries, for example, by the United Kingdom Standard Industrial Classification of Economic Activities is based on SIC codes.
In 1997, the SIC classification was replaced in the United States by the North American Industry Classification System (NAICS code).