When you are promised a "rate lock" from a lender, it means that you are guaranteed to get a set interest rate over a certain number of days for the application process. This protects you from working through your whole application process and finding out at the end that your interest rate has gotten higher.
Rate lock periods can be various lengths of time, anywhere from 15 to 60 days, with the longer spans usually costing more. You can get a longer period for your lock, but in making this choice, will probably have a higher rate than you would have with a shorter span of time
In addition to going with a shorter lock period, there are other ways you can attain the best rate. The bigger the down payment, the better your interest rate will be, because you will be starting with more equity. You can pay points to improve your interest rate for the loan term, meaning you pay more up front. One strategy that is a good option for many people is to pay points to bring the rate down over the term of the loan. You'll pay more up front, but you will come out ahead, especially if you keep the loan for a long time.
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