The annual interest rate refers to the deposit interest rate for one year. The term "interest rate," abbreviated as "IR," signifies the ratio of the interest amount to the principal of a deposit or loan within a specified period. It is generally classified into three types: annual interest rate, monthly interest rate, and daily interest rate. The annual interest rate is expressed as a percentage of the principal, the monthly interest rate is expressed as a per mille of the principal, and the daily interest rate is expressed as a per ten thousand of the principal.