Interest can be thought of as a reward for saving money. When you save money, Greylock pays you a small amount of extra money (interest) for keeping your money with us. With compound interest, think of it like a snowball rolling down a hill. It gets bigger and bigger over time, not just because of the new snow, but also because of the snow it's already gathered. Your original interest starts earning more interest, making your money grow faster. Here's an example:
If you save $100 and your CU gives you 5% interest each year, you'll get $5 extra each year. With compound interest, you'll earn interest on that $5 too, and the next year, you'll have a little bit more interest to earn interest on, and so on.
Check out our Money Mindset blog post on Compound Interest to learn more!