PPT Slide
Ideally, yield curve should be plotted for bonds that are alike in all respects other than the maturity; but this is extremely difficult in practice. Bonds that have similar risks of default may be different in coupon rates, marketability, callability, etc.
Benchmark interest rate or base interest rate
Yield curve on US Treasury bond instruments is used to serve as a benchmark for pricing bonds and to set yields in other sectors of the debt market. This is because the US Treasury bonds are viewed as default free and they have the highest liquidity.