1. They gain a certain amount of ownership in the company. They can vote on things that management brings up.
2. They can go for capital gains. That means that if you buy something at 30 dollars and sell it to someone else when it hits 40, each share that you bought will bring a profit of 10 dollars.
3. They can receive dividends. That means if the company makes money after it has paid all its obligations, and it decides to pay you something for each share you hold, you have been paid an amount that is equal to what each share will bring in * the number shares.
