"Rate Lock" and other Ways to Get a Lower Interest Rate
Freezing the Rate
A rate "lock" or "commitment" is a lender's promise to freeze a certain interest rate and a specific number of points for you for a specified period during your application process. This ensures that your interest rate can't get higher as you are going through the application process.
Rate lock periods can be various lengths of time, between 15 to 60 days, with the longer ones usually costing more. The lender will agree to freeze an interest rate and points for a longer span of time, say sixty days, but in exchange, the rate (and sometimes points) will be more than that of a rate lock of a shorter period.
Other Interest Saving Strategies
There are other ways to get a reduced rate, besides opting for a shorter rate lock period. The larger down payment you pay, the lower the interest rate will be, since you will have more equity from the start. You might opt to pay points to lower your interest rate over the loan term, meaning you pay more up front. For a lot of people, this makes financial sense..