Bonds that are backed by assets are called secured bonds and those that are not backed by assets are called unsecured bonds.
Bonds can be secured by creating a charge against certain assets of the company to raise debt. Assets can be in the form of property, machinery etc or liquid in the form of stocks. As the name suggests, secured bonds are usually considered to be safer than unsecured bonds as the risk of repayment is higher in unsecured bonds. Unsecured bonds are also called debentures.

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