Investing in the stock market is a great way to make a lot of money, but getting started can be tough. There are seemingly endless options when it comes to choosing where to invest, and investing in the wrong stocks could put your money at risk. If you're new to investing, though, there's one type of investment that outshines the rest: S&P 500 index funds. Image source: Getty Images. What is an S&P 500 index fund? First, it's important to understand what, exactly, an S&P 500 index fund is. The S&P 500 is a stock market index that includes 500 of the largest companies in the country. An index fund is a collection of stocks that tracks a particular stock market index. In other words, the index fund will contain whatever stocks are included in the index. So when you invest in an S&P 500 index fund, you're investing in all of the companies in the S&P 500. S&P 500 index funds can be a great option, especially for new investors. And there are five good reasons to consider this type of investment. 1. You don't need to do lots of research When you invest in individual stocks, you'll need to thoroughly research each company you're considering. Some stocks are riskier than others, and it's important to make sure the company you're investing in is financially healthy. When you invest in an S&P 500 index fund, however, you don't need to worry as much about the stocks in the index. The S&P 500 is recognized as one of the best representations of the stock market as a whole, and it has experienced an average 10% annual rate of return since it was founded. With that type of track record, you can rest assured that your investments will see positive returns over the long run. 2. They're one of the most affordable types of investments When it comes to funds, there are two main types: passive funds and actively managed funds. Actively managed funds have an expert hand-selecting every stock in the fund, while passive investments do not. Index funds are passive investments because they mirror certain indexes. An S&P 500 index fund contains all of the stocks in the S&P 500 itself, so there's no fund manager choosing which stocks to include. This makes them less expensive than actively managed funds, because you're not paying an expert to pick stocks. 3. They're more likely to recover from market downturns No investment is immune to risk, and S&P 500 index funds are no exception. However, they're more likely than other investments to recover from market crashes. The S&P 500 has experienced its fair share of volatility over the years, but it's always been able to bounce back. Over the past 20 years, the S&P 500 has seen the dot-com bubble burst, the Great Recession, terrorist attacks, wars, civil and political unrest, and a global pandemic -- yet it continues to climb. ^SPX data by YCharts It's very likely the market will experience more volatility over the next few years and decades. But if history shows us anything, it's that the S&P 500 will pull through. 4. They provide instant diversification Diversification is key when investing. That's because the more stocks you invest in, the more likely it is that your portfolio will remain strong even if a few of those stocks don't perform well. When you invest in an S&P 500 index fund, you're immediately investing in 500 different companies -- all within a single investment. It's always a possibility that some of those companies will take a turn for the worse. But when you're investing in hundreds of stocks, it won't make a significant difference if a few stocks tank. 5. They include stocks from some of the strongest companies in the country There are many different indexes out there, but the S&P 500 is one of the strongest. That's because only the best and the biggest companies are allowed a spot in the index. To be included in the S&P 500, a company must meet several basic requirements regarding its size and profitability. If it meets all the requirements, it then must be approved by a committee before it can join the S&P 500. Some of the biggest companies in the S&P 500 include Apple, Microsoft, Amazon, Facebook, and Alphabet. By investing in an S&P 500 index fund, you'll be investing in all of these companies and more. Getting started investing can be intimidating, but it's easier than you may think. S&P 500 index funds are perfect for new investors, and they can help you start your investing journey off on the right foot. 10 stocks we like better than WalmartWhen investing geniuses David and Tom Gardner have an investing tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Walmart wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks Stock Advisor returns as of 2/1/20John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Teresa Kersten, an employee of LinkedIn, a Microsoft subsidiary, is a member of The Motley Fool's board of directors. Randi Zuckerberg, a former director of market development and spokeswoman for Facebook and sister to its CEO, Mark Zuckerberg, is a member of The Motley Fool's board of directors. Katie Brockman has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Alphabet (A shares), Amazon, Apple, Facebook, and Microsoft and recommends the following options: long January 2022 $1920 calls on Amazon and short January 2022 $1940 calls on Amazon. The Motley Fool has a disclosure policy.Source