Bond is an instrument of indebtedness of the bond issuer to the holders. Government, corporations and companies issue bonds to raise fund. Buying bonds is same as lending fund to the issuers, issuers are obliged to pay them interest (the coupon) and/or to repay the principal at a later date, termed the maturity. Bond holders can choose to hold to bonds until it matures or sell it before maturity at the market price.