Ally Financial reports that compound interest is a powerful tool that helps savings grow faster by earning interest on both the principal and accumulated interest.

One of the upsides to keeping your money in a bank account is the chance to earn compound interest — you earn interest on both the funds you deposit in an account and on the interest that money earns.

CNBC Select defines compound interest, how it works and ways to take advantage of it if you're looking for a new credit card ...