In stock market terminology, the term Stock refers to the shares of a corporation which represent an ownership interest in that corporation. Stocks can be issued privately or can be offered to the public and traded on an exchange.
For example, assuming a company that has been doing business for a period of time with a proven amount of success, would like to expand and offer its products to a wider audience. Nevertheless, it lacks financing to make this possible. By offering stock to either an outside investor or by selling the stock on the open market to the public, the company can raise the funds needed to finance the expansion. By implementing this equity financing, the company is effectively selling an equity interest representing ownership in the company to outside investors.