A rate "lock" or "commitment" is a promise from the lender to set a specific interest rate and a particular number of points for you for a certain period during your application process. This means your interest rate won't get higher while you are going through the application process.
Rate lock periods can vary in length, anywhere from 15 to 60 days, with the longer ones generally costing more. You can get a longer period for your lock, but in making this choice, will most likely have a higher rate than you would have with a shorter period
There are more ways to get a better rate, in addition to choosing a shorter rate lock period. A bigger down payment will get you a lower interest rate, because you will have more equity from the beginning. You can pay points to bring down your rate for the loan term, meaning you pay more initially. To many people, this makes sense and is a good deal..
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