The annualised percentage rate (APR) is the interest rate on a deposit for one year. The interest rate, short for "interest rate", is the ratio of the amount of interest to the principal amount of a deposit or a loan over a certain period of time. There are three types of interest rates: the annual interest rate, the monthly interest rate and the daily interest rate. The annual interest rate is expressed as a few per cent of the principal, the monthly interest rate as a few thousandths, and the daily interest rate as a few ten thousandths.