Amortisation refers to the principal amount of the debt being repaid in instalments over the life of the loan. It can be contrasted with a bullet repayment where the principal is paid in one instalment at the end of the life of the loan.
The repayments in an amortising loan are often split into equal amounts, payable at regular intervals, for example quarterly or six-monthly. Another common repayment structure for amortising loans, is for the final instalment to be larger than the rest. This is known as a 'balloon repayment'. Alternatively, If the borrower's business is seasonal, the repayment instalments may reflect this with the borrower obliged to make larger repayments when its cashflow is forecast to be at its highest.
Interest is typically calculated at regular intervals on the outstanding principal of a loan. Therefore, the key advantage of using an amortising payment schedule is that, because the outstanding principal regularly reduces, less interest is payable overall than would be the case with a bullet repayment.