Distributions from investment income, usually expressed as a percentage of net asset value or market price. Unlike total return, yield is a single component of investment income and does not include capital gains distributions or capital appreciation of underlying shares.
The Yield Curve gives the relationship between yields on a group of fixed-income securities with varying maturities at a given point of time viz. treasury bills, notes, and bonds. Although the curve can be flat or even inverted but it typically slopes upwards as longer maturities have higher yields.
After taking into account components like purchase price, redemption value, time to maturity, time between interest payments and coupon yields, it is used to determine the rate of return for an investor for long term, interest-bearing bonds held to its maturity.