Industry codes (NAICS, SIC) are hierarchic, numeric schemes to define and distinguish one industry from another. Industries are grouped by similar production process. NAICS codes are most frequently used, though some publishers use SIC codes. About Industry Classification Codes
Industry information is found in trade journals, association websites, industry/investment analysts’ reports, nonprofit and government information sources (eg. EPA Industry Letters, EIA reports, Economic Census), market research reports, and commercial industry reports.
For industry research, one needs essential facts as well as in-depth analysis. Read trade journals that focus on the industry. Consult industry association publications, websites and datacenters for the data compiled about their industry.