The stock market is made up of exchanges, like the New York Stock Exchange and the Nasdaq. Stocks are listed on a specific exchange, which brings buyers and sellers together and acts as a market for the shares of those stocks. The exchange tracks the supply and demand — and directly related, the price — of each stock.
But this isn’t your typical market, and you can’t show up and pick your shares off a shelf the way you select produce at the grocery store. Individual traders are typically represented by brokers — these days, that’s often an online broker. You place your stock trades through the broker, which then deals with the exchange on your behalf.
The NYSE and the Nasdaq are open from 9:30 a.m. to 4 p.m. Eastern, with premarket and after-hours trading sessions also available, depending on your broker.