The North American Industry Classification System (NAICS pronounced Nakes) is a unique, all-new system for classifying business establishments. Adopted in 1997 to replace the old Standard Industrial Classification (SIC) system, it is the industry classification system used by the statistical agencies of the United States. Read all about it at this US Census Bureau site.
Some sources of industry data still use SIC codes, even though they've been replaced by NAICS.
These reports are often very expensive, however, sometimes summaries and abstracts can provide useful insights. And occasionally, firms may share the Executive Summary free.
For the following sites, we don't have subscriptions. We only have access to whatever material/abstracts/summaries are free.