A mortgage is a loan that is used to pay for a portion of the price of real estate. The loan typically requires a fixed schedule of repayments. The underlying real estate is used as collateral on the loan. If the borrower does not make loan payments on a timely basis, the lender can seize and sell the property, using the proceeds to pay off the remaining loan balance. The most common mortgage is the fixed-rate variety, which locks in a fixed interest rate for the life of the loan. An adjustable-rate loan is also available, which tracks the prime rate. Adjustable-rate loans are riskier for the borrower, since a jump in the prime rate can trigger a substantial increase in mortgage payments.