Do people eventually make money from owning stocks in a startup? Like if I own stock in a startup, what do I have to look for or know to eventually sell my shares and make money? Is it only when the company goes public does one make money?

The equity you have in a startup is only valuable when there is a market for it (goes for any stock). When a startup goes public, and lists in a stock market, a market is created and you could then make money by selling your shares. Alternately, there could be a buyer for your shares outside the primary/secondary market - this is what happens when someone buys/acquires the startup, and pay all its shareholders an agreed price for their shares. Apart from IPO and acquisition, a revenue-generating business could also pay dividends to its shareholders, thus leading to you earning money from your shares. However, most startups are pre-profit or are in the habit of investing their profits back into the business. Hence, the chances of dividend payout might be slim. As to the question of whether you will make money from the shares you hold in a startup, this is dependent on a number of factors: 1) Likelihood of successful exit: how successful the startup is likely to be, the chances of it going public at a decent price, the chances of it being acquired by someone... 2) If you are an employee and stock options are awarded to you, the grant conditions are important as well - e.g. vesting rules in the event of an acquisition, rights to convert shares etc. 2) If you are an investor, the conditions around the stake awarded to  you and other investors is important - e.g. preferred vs. common stock. If you are an employee, you are likely to hold common stock which is junior to any preference shares held by investors. These factors affect how much money you could make from your stake in the startup in the event of a successful exit.

You can earn money through exit or through selling your shares to other people (investors) Exit don't have to be public - it can be a private sale to other people or acquisition by other company. If you defne your shares and a "founer class shares", convertible to preferred in case of 2nd or higher round of funding you should be able to sell some of your shares and to realize some gains before the exit. Do not do this at the 1st round - this seems like unreasonable and investors would not invest if they would know you are planning to sell your starer at the beginning. Also, make sure to remove first refusal rights out of your shares, as this would prevent you from selling your preferred shares to higher bidder.