Yes, a shareholder is one who owns stocks. But you can say there's another tier, if you own say 10% of a company's stock you may actually get to influence how the company runs. That is called the board of directors. They decide what path the company goes down, the CEO, etc. (Technically it's the shareholders that decide, but your 1 millionth voting power isn't doing anything when your local billionaire has a billion dollars more stock than you.)