When you borrow money, you’ll also pay interest on top of the amount you borrowed.. Interest is the money the lender gets for loaning you the money. Read Next: 5 Subtly Genius Moves All Wealthy People ...

Annual percentage yield (APY) is the effective annual rate of return on an investment. Learn how it accounts for compounding interest and how it differs from APR.

The Rule of 72 is a shortcut or rule of thumb used to estimate the number of years required to double your money at a given annual rate of return and vice versa.