A stock exchange is a marketplace where shares of publicly traded companies are bought and sold. It provides a platform for investors to trade stocks, which represent ownership in a company. The prices of these stocks fluctuate based on supply and demand, allowing investors to potentially earn profits or incur losses. Major stock exchanges, like the New York Stock Exchange and the NASDAQ, facilitate these transactions and ensure fair trading practices. They also provide important information, such as stock prices and trading volumes, helping investors make informed decisions. Overall, stock exchanges play a crucial role in the global economy by enabling capital flow and investment.