Callable bonds are bonds that can be bought back, or redeemed, by the bond issuer before the bonds reach maturity. The issuer usually pays a premium to the bond par value if it calls the bonds. This premium compensates investors for the "call risk." Call dates and call prices are specified in the bond agreement. Because callable bonds face call risk, the yield measure often preferred by investor is yield-to-call. This is the yield an investor earns if the bond is called on its next call date.