The most common type of mortgage program where your monthly payments for interest and principal never change. Property taxes and homeowners insurance may increase, but generally your monthly payments will be very stable.
Fixed rate mortgages are available in various different terms. There are also "biweekly" mortgages, which shorten the loan by calling for half the monthly payment every two weeks, the benefit of a bi-weekly mortgage includes paying your loan off earlier and saving you money by paying less interest over the life of the loan.
Fixed rate fully amortizing loans have two distinct features. First, the interest rate remains fixed for the life of the loan. Secondly, the payments remain level for the life of the loan and are structured to repay the loan at the end of the loan term.
During the early amortization period, a large percentage of the monthly payment is used for paying the interest. As the loan is paid down, more of the monthly payment is applied to principal.