ELI5: Explain Like I'm 5

Stock market index

Have you ever seen a big chart with lots of numbers going up and down on it, and people talking about it on the news? That's called the stock market. A stock market index is like a special chart that tracks the overall performance of lots of different companies that are on the stock market.

Imagine you and your friends are all selling lemonade. You're all different ages and have different recipes, but you're all selling lemonade. Your parents give you each some money to start your lemonade stand. As the day goes on, different kids sell more lemonade than others. Maybe you sell 10 cups, but your friend sells 15 cups. You might feel a bit upset at first, but then everyone helps add up how much lemonade each of you sold to see who made the most money.

A stock market index is like that list of who sold the most lemonade. It looks at lots of different companies (like you and your friends with lemonade stands), and adds up how well they're doing. Then it shows that information on a chart, so that people can see how well the overall stock market is doing.

For example, the most famous stock market index is the Dow Jones Industrial Average. That index looks at the performance of 30 big companies (like Apple, Coca-Cola, and McDonald's), and adds up their overall performance. If the companies are doing well and making lots of money, then the index goes up. But if they're not doing so well and losing money, the index goes down.

So, just like how you and your friends want to make the most money selling lemonade, the companies on the stock market want to make the most money too. And the stock market index helps people keep track of how well they're doing.