Classification systems are used by Industry and Federal statistical agencies to standardize the collecting, analyzing, and publishing of statistical data related to the U.S. and North American business economies. In these reports find labor statistics, numbers of companies in a particular area, salaries, earnings, trends in the industry, etc.
What are SIC and NAICS?
SIC (Standard Industrial Classification) system was developed by the US Government to allow comparison of data and statistics among businesses and industries according to their primary business activity. The SIC was used by many government agencies until it was updated to the newer NAICS (North American Industrial Classification System in 2004. Between 1997 and 2004 both systems were in use. After 2004, only NAICS is used.
SICcode.com Use this link to see a chart that converts SIC to NAICS codes