A debenture is a type of loan issued by a company to raise funds. There are different types of debentures based on security, redemption period, record keeping, and convertibility. Debentures offer companies a way to raise funds for a specific period without diluting ownership, but carry more risk than shares if the company fails to repay on time. Debenture holders are creditors entitled to interest payments, while shareholders are owners entitled to potential dividend payments from company profits.