Amortization is the process by which loan principal decreases over the life of a loan, typically an amortizing loan. As each mortgage payment is made, part of the payment is applied as interest on the loan, and the remainder of the payment is applied towards reducing the principal.
An amortization schedule, a table detailing each periodic payment on a loan, shows the amounts of principal and interest and demonstrates how a loan's principal amount decreases over time. An amortization schedule can be generated by an amortization calculator.
Negative amortization is an amortization schedule where the loan amount actually increases through not paying the full interest.
Should you therefore fix your rate or rather opt to reduce your balance?
Staying on a variable rate means that you will also benefit from any further cuts the Reserve Bank may make. And if you have an access-type bond, you will always be able to withdraw any additional amounts paid into your bond account should you need them in an emergency.