YTM and spot rate

What will the YTM be for a bond with the Interest rate changing ? YTM is the discount rate used on all cpn + principal payment, but with the Interest rate changing, ie discounting using spot rate, what would the YTM be and what does it measure?

YTM is going to change too because bond value is going to change. YTM is IRR of the following cash flows: CF0: = - Bond Price CF_i = coupon payment (i = 1 … n) CF_T = principal payment bond price is the sum of discounted cash flows (using spot rates) and therefore going to change because of interest rate changes. As a result YTM is going to change too.