How does amortization work?
Amortization is the elimination of a debt over time with periodic payments.
Each periodic payment is applied first to the accrued interest, with the remainder applied to the outstanding principal amount. As time goes on, a larger portion of each repayment will be applied to the outstanding principal because less interest is accrued on the outstanding principal amount as it is lowered by prior periodic payments.
If additional fees have been applied to the loan (for example, a late fee), your payment will cover those first, followed by interest and then principal.