Each of the following resources can be used to find company profiles. Company profiles may include such information as corporate history, executive leadership, financial performance, market share, and more. The more you know about a company, the better prepared you will be to ask (and answer!) deep and insightful questions during your interview.
Don't forget to look for a company's own website, too. Large public companies are especially likely to have detailed information, including annual reports and financial statements, available on their corporate websites. Social media such as Facebook and Twitter can also provide useful company information.