NAICS (North American Industrial Classification System) codes describe specific industries, and make finding industry information easier.
NAICS codes replaced SIC (Standard Industrial Classification) codes in 1997. However, some sources still use SIC codes. It is always a good idea to have both NAICS and SIC codes when you are doing industry research.
You can find both NAICS and SIC codes at the Census cite, or at sites like SIC code.
There are many books and ebooks in our collection about companies. You can search the library catalog by the name of the company to find them.