Industry classification codes allow you to identify, define and categorize industries. You can use them in many databases to find information by industry.
North American Industry Classification System (NAICS): Adopted in the 1990s by the U.S., Canada, and Mexico to categorize industries. Replaced the SIC system (see below).
Standard Industrial Classification (SIC): SIC is a four-digit classification system developed in the 1930's for use by the U.S. federal government. Although still used in some databases, the SIC classification system is no longer being revised.
International Standard Industrial Classification (ISIC): maintained by the U.N. Statistics Division, the ISIC is used in a number of international databases, such as ILO's LABORSTA. Rev.4 is the current version. See link on sidebar at this site to other available classifications.