In the US, fixed rate mortgages are fixed for the entire term of the mortage. Anything else is called an adjustable rate mortgage (ARM) and those are often 3/1, 5/1, 7/1, or 10/1 (referring to the length, in years, of the original rate and then the period, in years, of each subsequent adjustment period [note that if you see a /6 mortgage, that's adjustable every 6 months after the initial period, not every 6 years]).

It used to be that ARMs would have a "teaser" rate for that first period, which made them make sense to take out for some circumstances. Now, fixed rates dominate because the ARM rates aren't much lower than the fixed rates.