Outstanding shares refer to all the shares that have been issued by a company and are currently held by investors, shareholders or other stakeholders. These shares represent ownership in the company and can be traded on public stock exchanges. The total number of outstanding shares is an important metric used to calculate key ratios such as earnings per share (EPS), price-to-earnings ratio (P/E) and others that help investors make informed decisions about a particular company's performance, valuation and potential for growth.