Amortization is a term that id used during the processing of a loan. During the loan the lenders ask for some initial payment that is only as the interest of the total duration that time you may see that you already paid much you principal amount did not changed remarkably that it should be. It is because of the initial amount paid you considered as the interest that will occur in the term of loan. As the months you will see the reduced principal because when all the interest is deducted the payment will gradually reduce your principal amount.
For example if you monthly payment is $500 they will take $400 as interest and $100 will reduced form the principal as the month will pass the interest amount will be nil and from that time monthly amount will be reduced from the principal directly.