A bond is an interest-bearing promissory note or a long term (I. O. U). It could be regarded as a promise to pay a stated rate of interest for a definite period of time and to repay the principal at a specific date of maturity.
A secured bond have specific asset pledge as security in case of default on the loan, while an unsecure bond is usually regarded as a mere creditor in case of default.
The terms and conditions attached to a bond is usually contain in indenture which is a formal contract between the borrowing party and the creditor.