Your mortgage will likely be the longest loan you ever have - you could be paying it for as much as 30 years! This period is called the 'amortization' period. It indicates the amount of time it will take to pay off the mortgage loan, assuming you make all payments in full and on time.
In general, the shorter your amortization, the less you pay in interest costs over the life of your mortgage. So, if you amortize your mortgage over 15 years instead of 25 you can save thousands of dollars in interest costs.
Good deal? Usually. The only challenge is whether you can afford the larger payments. A shorter amortization will always translate as higher mortgage loan payments - because you are paying off the mortgage loan more quickly. Usually, you should attempt to pay the highest mortgage payment which is comfortable for your family, but still leaves you the ability to save for a rainy day.