Why is the yield to maturity (YTM) of a discount bond greater than the bond's current yield?

The yield to maturity (YTM) of a discount bond is greater than the bond's current yield because the YTM takes into account the total return an investor would receive if they hold the bond until maturity, including the capital gain from buying the bond at a discount. The current yield only considers the annual interest payments relative to the bond's current price, without factoring in the potential gain from the bond reaching its full face value at maturity.