The Vanguard S&P 500 ETF is an investment fund that aims to track the performance of the S&P 500, which is a stock market index representing 500 of the largest publicly traded companies in the United States. This ETF allows investors to buy a single share that gives them exposure to a diverse range of companies, including well-known names like Apple and Microsoft. Investing in the Vanguard S&P 500 ETF is popular among individuals looking for a low-cost way to invest in the overall U.S. stock market. It typically has lower fees compared to actively managed funds, making it an attractive option for long-term investors seeking growth through broad market exposure.