What are index funds?
Index funds are investment funds that follow a benchmark index, such as the S&P 500 or the Nasdaq 100. When you put money in an index fund, that cash is then used to invest in all the companies that make up the particular index, which gives you a more diverse portfolio than if you were buying individual stocks.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What are index funds?
### Input: 
### Response: Index funds are investment funds that follow a benchmark index, such as the S&P 500 or the Nasdaq 100. When you put money in an index fund, that cash is then used to invest in all the companies that make up the particular index, which gives you a more diverse portfolio than if you were buying individual stocks.