An Index Fund is a type of investment fund that aims to match the performance of a specific market index, like the S&P 500, rather than trying to beat it. Instead of picking individual stocks, the fund invests in all or most of the companies that make up the index. This approach offers broad diversification, typically lower fees, and a simple way to invest in the overall market. Index funds are often recommended for long-term investors because they provide steady exposure to the market without requiring active management or frequent trading.