Depending on which side of the transaction you are on, interest is either the cost of borrowing money or the reward for saving or investing it. If you are a borrower, interest is a percentage of the loan amount you will owe the lender over a year, known as the interest rate. Conversely, if you are a saver or investor, you receive an annual percentage yield (APY). For instance, if you borrow money, the lender charges you interest on top of the amount borrowed. In contrast, i