A stock exchange is a marketplace where shares of publicly traded companies are bought and sold. Investors can trade stocks, which represent ownership in a company, and the prices of these stocks fluctuate based on supply and demand. Major stock exchanges, like the New York Stock Exchange and the NASDAQ, provide a platform for these transactions, ensuring transparency and regulation. Stock exchanges also play a crucial role in the economy by enabling companies to raise capital through the sale of shares. When a company goes public, it lists its shares on a stock exchange, allowing investors to purchase them and potentially earn returns as the company grows.