Short-term mortgages offer lower interest rates than long-term mortgages. You save money by the lower interest rates and shorter payment period. The trade off is a larger monthly payment, but this option can save you thousands.
Changing the term of your mortgage can help in several ways. First, if you were to refinance your current mortgage from 30 years to 15 years, you will accelerate the rate at which you pay towards principle each month meaning your house will be paid off quicker. Also, you will save an unbelievable amount of money in terms of interest because you would likely be taking 10 to 15 years off the life of your loan. Second, you can also refinance a 15 year mortgage to a 30 year mortgage. It seems like it might not make sense to do this, but if you have an immediate need to free up monthly cash-flow and you don't want to take out a home equity loan, this can work out to your benefit. When you take a 15 year loan and refinance it to 30 years you will have the same balance only the payments can be hundreds of dollars less than the 15 year loan. The only draw back to this is you will pay more in interest over the live of the loan.
If you do not plan on staying in the house very long, refinancing may not be in your best interests.
For both new buyers and refinancers, it's important to understand what a no-cost mortgage loan or a no-cost refinance loan really means. "No cost" does not mean that closing costs (also known as settlement costs) have been erased. It means that the closing costs will be factored into the interest rate associated with the loan. Of course, this also means that, all other things being equal, the interest rate associated with a no-cost mortgage will always be higher than one where the borrower pays the closing costs up front.