Mortgage rates describe the range of interest charges a lender might apply to a loan for home purchase, refinancing or improvements. The going rates are determined by a number of factors, but are often pegged to such things as mortgage-backed securities or mortgage bonds. In general, mortgage rates will be lower for those with impeccable credit and much higher for those with blemishes in their past. Knowing what mortgage rates will be applied to a loan is essential for determining the true costs of borrowing. The interest rates paid over the course of a loan, which are shown in an amortization schedule, can easily double or even triple the anticipated cost of buying beyond the initial sticker price.