A rate lock or a rate commitment is a lender's promise to hold a certain interest rate and a certain number of points for you, for a specific period of time while your application is being processed. This prevents you from going through the entire process, only to find out that the interest rates have risen.

There are various time lengths and longer ones usually will cost more. There are many ways other than opting for a shorter rate lock period to get a lower rate. A larger down payment will result in a lower interest rate because you are starting with more equity. You are able to pay points to lower your rate over the length of the loan, however you would need to pay more up front.

Closing costs are fees paid by the lender, which are charged to you to close the loan. Most people settle the costs when they sign at the closing, but others finance their closing costs. Paying closing costs at closing will reduce your interest rate. The interest rate that is offered to you depends on your credit score and income-to-debt ratios.