When you're 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 your application process. This ensures that your interest rate will not go up as you are going through the application process.
Rate lock periods can vary in length, anywhere from fifteen to sixty days, with the longer ones generally costing more. 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
There are more ways to get a low rate, in addition to going with a shorter rate lock period. A larger down payment will give you a reduced interest rate, because you are starting out with more equity. You can pay points to bring down your rate over the loan term, meaning you pay more up front. To many people, this makes sense and is a good deal..
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