When you are offered a "rate lock" from a lender, it means that you are guaranteed to keep a particular interest rate for a certain number of days for the application process. This prevents you from going through your whole application process and finding out at the end that the interest rate has risen higher.
Rate lock periods can be various lengths of time, anywhere from 15 to 60 days, with the longer period usually costing more. You can get a longer period for your lock, but in doing so, will likely have a higher interest rate than you would with a shorter span of time
In addition to opting for a shorter rate lock period, there are more ways you can score the best rate. A larger down payment will result in a lower interest rate, since you'll have a good deal of equity from the beginning. You may opt to pay points to improve your interest rate over the loan term, meaning you pay more up front. To many people, this makes sense and is a good deal..
Do you have a question regarding a mortgage program?