A fixed-rate mortgage means that you’ll pay the same interest rate throughout the life of your loan. On the other hand, an adjustable-rate mortgages starts out with a low interest rate for a set period of time (three or five years are common), and then adjusts according to market rates. In a low-rate environment, like we’re currently in, it’s generally beneficial to lock in a fixed rate, unless you only plan to be in the home for a short period of time.
Source: Motley Fool