The US Securities and Exchange Commission's mission is to protect investors, maintain fair, orderly, and efficient markets, and facilitate capital formation. All companies, foreign and domestic, are required to file registration statements, periodic reports, and other forms electronically through EDGAR. Anyone can access and download this information for free. Here you'll find links to a complete list of filings available through EDGAR and instructions for searching the EDGAR database.
When researching industry information, it is helpful to find the NAICS or SIC code for that industry, though all the industry databases also allow a keyword search. The federal government assigns these codes to business segments for data collection and reporting purposes. NAICS (North American Industry Classification System) codes were adopted in 1997 to replace the old Standard Industrial Classification (SIC) system. Many research resources, such as databases, utilize NAICS and/or SIC codes for searching purposes. You can search many of the library databases by NAICS and/or SIC code to get industry information.
Example 1: if you want to study the ice cream manufacturing industry, you would look up the 2007 NAICS code from the link, below, and note that it is 311520
A public company has shares of stock that represent an ownership interest in the company and those shares are traded openly on one or more stock exchange like the NASDQ or NYSE. Public Companies in the United States must file various forms and documents with the U.S. Securities and Exchange Commission detailing their financial performance and governance structure. Because of these regulatory requirements, information on many public companies is relatively easy to find.
A private company is a company that is not traded on any stock exchange. Private companies as a general rule do not have to file any documents with the U.S. Securities and Exchange Commission. Consequently, finding information on private companies can be quite challenging.