At the stock exchange, people called stock brokers work out deals for investors. The investor is the person who has the money, and the stock broker is the person buying and selling shares for him.
When someone buys a share of a company, he or she is hoping that the company’s value will go up. The higher it goes, the more money the person will make. That is because the share represents a percentage of the company, not a dollar amount. When the whole thing gets bigger, the little piece gets bigger too.