# Interest rate - Price of Credit vs Price of Money

I read somewhere that interest rate as the price of money is wrong but rather it is the price of credit. Can someone elaborate and explain what this means?

$$P = \sum_{n=1}^N \frac{C + M[{I_{n=N}}]}{(1+i)^n}$$
Where $$i$$ is the contractual interest rate, $$C$$ is the coupon payment, $$N$$ is the number of payments, $$I_{n=N}$$ is an indicator function taking the value of $$1$$ when $$n=N$$ is $$true$$ or $$0$$ otherwise, $$P$$ is the market price of the bond, $$M$$ is the value of the bond at maturity.