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While the descriptions and definitions of NAICS/SIC codes are standardized, the application of a particular code to a particular entity is not. Individual companies can choose their primary NAICS/SIC codes at their own discretion, and research firms may sort companies by varying codes based on their own criteria for analysis. Searching by NAICS or SIC in different databases may produce lists of different companies and competitors.
Industry Classification Codes define or classify industries based on what they do and how they do it. Links to resources for the two industry codes most commonly used in the United States (NAICS and SIC) are listed below:
Knowing the full breakout will help you understand what level of analysis the Industry Research Reports, Financial Ratios, etc. are providing:
2007 NAICS codes and descriptions/definitions
1987 SIC codes and descriptions/definitions