A rate "lock" or "commitment" is a promise from the lender to freeze a certain interest rate and a specific number of points for you for a specified period of time while your application is processed. This ensures that your interest rate can't rise while you are working through the application process.
Rate lock periods can be various lengths of time, anywhere from 15 to 60 days, with the longer spans typically costing more. You can get a longer period for your lock, but in making this choice, will probably have a higher interest rate than you would have with a shorter rate lock period
There are other ways to get a good rate, in addition to going with a shorter rate lock period. A larger down payment will give you a better interest rate, because you will have more equity at the start. You can pay points to bring down your interest rate over the life of the loan, meaning you pay more up front. For many people, this makes sense and is a good deal..
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