If it's the same as in the UK, Australia and NZ, then the rates are "fixed" for sub-durations within the overall length of the mortgage/home loan, and at the en

If it's the same as in the UK, Australia and NZ, then the rates are "fixed" for sub-durations within the overall length of the mortgage/home loan, and at the end of the sub-duration, you negotiate what the "fixed" rate is for the next sub-duration with the bank / mortgage lender. So for a twenty year "fixed" mortgage, you could end up splitting that into "fixed" rate chunks of 3 years, 3 years, 5 years, 3 years, 1 year, 3 years, years, 2 years. So the rate is "fixed" for what's often called the "fixed period" (sub-duration), giving you a bit of stability, but over the longer term of the overall mortgage, things can track interest rates more generally as you renew the rate.