The North American Industry Classification System (NAICS) is the hierarchical, numerical system used by the U.S. government to classify businesses in order to collect, analyze, and publish statistical data related to the U.S. business economy. It replaces the Standard Industrial Classification (SIC) System, although some resources still use the old SIC codes.
Separate codes exist for manufacturers, retailers, and wholesalers. Some resources may include only a company's assigned "primary" industry code. Primary codes apply to the company's main line of business. "Secondary" codes may appear if a company has multiple lines of business.
Many business databases can be searched using NAICS or SIC codes.