When (Fr−Ci) > 0 the bond will pay out a ”superior” interest payment than what the yield rate says to expect. As a result, the bond-buyer is willing to pay(lend) a bit more, P −C, than what will be returned at maturity. This extra amount is referred to as a ”premium”. On the other hand, if the coupon payments are less than what is expected according to the yield rate, (Fr−Ci) < 0, then the bond-buyer won’t buy the bond unless it is offered at a price less than C or, in other words, at a ”discount”.