A rate lock is a commitment made by a lender to a borrower to hold a specific interest rate and/or points for a specified period of time, usually until the loan closes. It is intended to protect the borrower from potential increases in interest rates during the loan process.

Rate locks are typically offered to borrowers who have applied for a mortgage and are in the process of shopping for a home. The rate lock period begins when the borrower and lender agree on the terms of the loan and ends when the loan closes. During this time, the lender agrees to hold the agreed-upon interest rate and points, even if market rates rise.

Rate locks are often offered at an additional cost to the borrower, either as a one-time fee or as a higher interest rate. Some lenders may offer rate locks for free or at a reduced cost if the borrower agrees to pay a higher interest rate after the lock period ends.

It's important to note that rate locks are not always available, and lenders may choose to discontinue them at any time. Borrowers should also be aware that rate locks are not guaranteed and may be subject to certain conditions being met, such as the loan closing within a certain time period or the borrower meeting certain credit criteria.