Fixed Rate

With a fixed rate mortgage, the interest rate does not change for the life of the loan; the monthly payment is always the same. The shorter the term of the loan, 25,20,15,10, the more attractive the rate will be.  

On a fixed-rate fully amortizing loan the payments are calculated to insure  that the loan is paid in full by the end of the term. In the early part of the mortgage period, a larger percentage of the monthly payment is applied to the interest on the loan. Over time, ashe mortgage is paid down, an increasing amount of the payment will be applied towards the principal.  

A 30 year fixed rate mortgage is the most popular type of loan as far as the security of having a fixed payment for the entire term as well as having a lower payment than a  15 year (or other shorter term) as the amortization (payback period) is longer. 

Benefits:

Lower monthly payments 
Interest rate does not go up
Payment does not go up, it stays the same 

A 15 year fixed rate mortgage allows you to pay down your loan more quickly and also saves on interest paid over time as well as offering a lower interest rate up initially.

Benefits:

Lower monthly payments than a 15 year fixed rate mortgage
Interest rate does not go up
Payment does not go up, it stays the same for 15 years   
Loan is paid off in shorter period with less interest