A rate "lock" or "commitment" is a lender's promise to set a particular interest rate and a certain number of points for you for a specified period of time while your application is processed. This protects you from working through your entire application process and discovering at the end that your interest rate has risen higher.
Although there are various lengths of rate lock periods (from 15 to 60 days), the longer spans are usually more expensive. A lender may agree to hold an interest rate and points for a longer period, like sixty days, but in exchange, the rate (and sometimes points) will be more than that of a rate lock of a shorter period.
There are more ways to get a lower rate, in addition to opting for a shorter rate lock period. A larger down payment will get you a lower interest rate, since you will be starting out with more equity. You can pay points to bring down your interest rate for the loan term, meaning you pay more up front. To a lot of people, this makes sense and is a good deal..
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