Both North American Industrial Classification System (NAICS) and Standard Industrial Classification (SIC) codes identify a company's primary business activity.
A NAICS code is a classification within the North American Industry Classification System.
SIC code identifies a very specific short descriptor of the type of business a company is engaged in.
Visit the North American Industry Classification System Association's free code look-up page to look up your NAICS code or to convert your SIC code to a NAICS code.