Interest rates are usually expressed as an annual percentage of the
amount borrowed. You can choose a mortgage with an interest rate that
is fixed for the entire term of the loan or one that changes throughout.
A fixed-rate loan gives you the security of knowing that your interest
rate will never change during the term of the loan. An adjustable-rate
mortgage (called an ARM) has an interest rate that will vary during
the life of the loan, with the possibility of both increases and decreases
to the interest rate and consequently to your mortgage payments.