Under the repayment method your monthly repayments consist of both interest and capital, so over time, the amount of money you actually owe will decrease. In the early years of your mortgage agreement, your repayments will be mainly interest and therefore the outstanding capital will reduce slowly at first.
This method ensures that the mortgage is repaid at the end of the term providing all payments are made on time and in full.
As a mortgage is secured against your home, it could be repossessed if you do not keep up with the mortgage repayments.