Debentures are debt instruments issued by companies to borrow money. They are similar to loans but documented as securities. There are different types of debentures that vary in their features: Ordinary debentures do not have security for the interest rate paid and the interest rate can vary. Mortgage debentures are secured by company property that can be sold to repay the debt if the company defaults. Redeemable debentures must be repaid after a certain period, while irredeemable debentures are only repayable if the company winds up. Registered debentures list the owner's name on the document, and convertible debentures allow conversion to company shares.