A rate "lock" or "commitment" is a promise from the lender to set a particular interest rate and a specific number of points for you for a certain period while your application is processed. This prevents you from going through your entire application process and discovering at the end that the interest rate has risen higher.
Rate lock periods can be various lengths of time, between fifteen to sixty days, with the longer period generally costing more. You can get a longer period for your lock, but in making this choice, will most likely have a higher rate than you would with a shorter span of time
There are other ways to get a low rate, in addition to opting for a shorter rate lock period. The larger down payment you can pay, the better the rate will be, as you will be entering the loan with more equity. You may opt to pay points to improve your rate for the life of the loan, meaning you pay more initially. For many people, this makes financial sense..
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