Interest is the price paid for borrowing money. There are several types of interest:
1) Fixed interest remains the same for the term of the loan, like a mortgage. Variable interest changes over time based on market rates.
2) Annual percentage rate (APR) includes interest and fees to make loan costs comparable.
3) Prime interest is what banks charge top customers; discounted interest offers lower rates as incentives.
4) Simple interest applies only to the principal, while compound interest applies to accumulated interest too, making it more costly over time.