It is easier to find information about public companies (those that sell stock to shareholders) than about private companies (those that are privately owned by an individual or group). Public companies in the United States are required to file documents with the Securities and Exchange Commission (SEC). These include the 10K (annual) and 10Q (quarterly) reports. In addition, public companies issue an annual report to shareholders.
When looking for information about a company, consider both for information from the company about itself (e.g., the company Web page, SEC filings, press releases, etc.) as well as information about the company written by others (e.g.., newspaper articles, analyst reports, articles by business school professors, etc.)
Finding information about a company includes the following steps:
Many of the business information resources will give you all of these types of information.