When you're promised a "rate lock" from the lender, it means that you are guaranteed to keep a specific interest rate for a determined period while you work on your application process. This saves you from working through your entire application process and finding out at the end that the interest rate has gone up.
While there are various lengths 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 likely have a higher rate than you would have with a shorter rate lock span of time
In addition to choosing the shorter lock period, there are more ways you may be able to score the lowest rate. The more the down payment, the smaller the rate will be, because you will be starting with more equity. You can pay points to improve your interest rate over the life of the loan, meaning you pay more initially. For a lot of people, this makes sense and is a good deal..
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