Common stock is a type of security representing a percentage of ownership in a company. This is the most prevalent type of security used by corporation. You may be familiar, as anytime you see a stock ticker symbol on the DOW or S&P 500 these almost always represent the price of one share of common stock (i.e. Apple). Private corporation will almost always issue common stock as well. Common shareholders usually can vote on leadership and in the event of liquidation common shareholders have the lowest rights to a company's assets only and are only paid after all other parties—bondholders, preferred shareholders and other debtholders—are paid in full.