A rate "lock" or "commitment" is a lender's promise to hold a certain interest rate and a specific number of points for you for a specified period while your application is processed. This keeps you from going through your entire application process and discovering at the end that your interest rate has risen higher.
Although there may be a choice of rate lock periods (from 15 to 60 days), the longer ones are typically more expensive. You can get a longer period for your lock, but in doing so, will most likely have a higher interest rate than you would have with a shorter rate lock span of time
There are other ways to get a better rate, besides going with a shorter rate lock period. The bigger down payment you can pay, the better the rate will be, since you will have more equity from the start. You might choose to pay points to reduce your rate over the term of the loan, meaning you pay more up front. One strategy that is a good option for many people is to pay points to improve the interest rate over the life of the loan. You'll pay more up front, but you'll save money in the long run.
Do you have a question regarding a mortgage program?