What is the difference between YTC, YTM, and Coupon?

Yield to maturity(YTM) is the effective return that an investor gets if he/she holds the Bond until maturity. In the case of callable bonds, Bonds can get called back by the issuer on the call date, so the callable date becomes a proxy for the maturity date. The effective returns calculated until this callable date is called the Yield to Call (YTC). The coupon of a Bond is the fixed interest that a Bond pays annually.