The first 2 digits of the NAICS represent general categories of economic activity, or sectors. The third digit designates the subsector, fourth digit stands for the industry group the fifth digit designates the NAICS industry and the sixth digit represents the national industry.
The first 2 digits of SIC stand for the major group (there are 11 total major groups), 3 digits represent the industry group and 4 digits designate the industry code.
On the NAICS website there are 3 different boxes for searching depending on the year you want the industry information for, 2012, 2007, 2002.
SIC/NAIC codes are standardized to the four or six digit level. Some sources will add additional digits to drill down to more specific industry level. The additional numbers read like decimals and represent a more specialized industry. These additional digits may or may not be uniform in different resources.
Many of the company databases allow a search using a NAICS or SIC code; this can be an easier way to search for companies within the same industry. Many sources provide industry information based on these codes. Most directories and online company databases that offer searching for companies by industry use either SIC or NAICS codes. A helpful alphabetic index of industries is in the back of the paper manual (HF1042 .A55 1987).
North American Industry Classification System (NAICS) is a 2-6 digit classification code that identifies an industry according to economic activity in Canada, Mexico and the U.S. There are 20 classification sectors. It was developed during the 1990’s to replace SIC codes. There is a detailed alphabetical product index found in the bound volume. Type in a 2-6 digit code or keywords to begin your search.
Standard Industrial Classification (SIC) is a 4 digit code that identifies an industry. This code was developed in 1937 by the U.S. Government, the last volume was published in 1987. A detailed alphabetical index can be found in the bound volume or on the web site under “examine the manual structure”. Type in a 2-4 digit code or keyword to being searching.
The codes are an accepted standard however the assigning of codes to companies is not centralized or standardized. Each source will assign codes based upon what that vendor determines what the company does and which industries of a diversified company are considered the most important. Different sources often list different codes for the same company.