There are a few different ways to approach the concept of duration, or a fixed-income asset's price sensitivity to changes in interest rates. The Macaulay duration is the weighted average term to maturity of the cash flows from a bond, and is frequently used by portfolio managers who use an immunization strategy. The modified duration of a bond is an adjusted version of the Macaulay duration and is used to calculate the changes in a bond's duration and price for each percentage change in the yield to maturity.