Industry Definition

Many sources arrange information about industries and companies by numerical coding systems such as NAICS and SIC.

Other sources develop their own word classification systems which vary in detail.

Common Industry Codes

North American Industry Classification System (NAICS)
Browse through classification (see 2012 NAICS on left side of screen) or search for specific products using forms in upper left.
Standard Industrial Classification Search (SIC)
Replaced by NAICS in U.S. government reporting, but many other sources still use the SIC system.
ThomasNet
Uses very detailed listing of products and their suppliers.