Company information is generated by a company itself (e.g., company website, SEC filings, press releases, etc.) as well as outside parties (e.g., newspaper and trade articles, analyst reports, etc.). Some company information, like analysis, cannot be obtained freely online. A lot of company information is proprietary (e.g., product level sales, manufacturing processes, etc.) and can not be found at all.
A public company has sold a portion of the business to the public via an IPO (initial public offering) and offers securities (e.g., stocks, shares, bonds, loans, etc.) for sale to the general public, typically through a stock exchange or over-the-counter market.
Domestic, public companies must file financial statements with the United States Securities and Exchange Commission and issue annual reports. A current annual reports can typically be found on a company's website. In addition, public companies tend to be written about more in the business and popular press. These factors lead to large amounts of company financial and business information being made available to the public and outside parties.
A ticker symbol (example: Apple Inc. = AAPL) is an abbreviation used to uniquely identify publicly traded shares of a particular stock on a stock exchange. A good way to find a ticker symbol is to use Google (search: Apple ticker). Many library databases and information tools can be searched by ticker symbol, which can lead to a more precise set of search results.
Ownership of a private company is held by a handful of people, often the founder and a few others. Private companies typically do not file financial statements with the SEC or disclose a lot of information to avoid leaking secrets to competitors. For these reasons, researching a private company is more challenging. You usually will not find extensive financial information for private companies. A current, annual sales or sales volume figure is the statistic most often reported. You may need to accept a revenue range or estimate or even inferred revenue based on information known or presumed. Depending on size, there is usually less published about private companies. For smaller, private companies much of the information that can be found is produced by the company itself.
Research a private company by:
A subsidiary is a company that is completely or partly owned and wholly controlled by another company. A parent company is a company that owns enough voting stock in another firm to control management and operations. Often financial data and other information for a subsidiary is limited and/or wrapped up with parent company information. You will want to look at both parent and subsidiary to obtain a complete picture. The Corporate Affiliations database linked below provides information on company hierarchies and some subsidiary data: