A debenture is a type of long-term debt instrument used by companies and governments to raise capital. It is essentially a loan that investors provide, and in return, the issuer promises to pay interest over a specified period and return the principal amount at maturity. Debentures are typically unsecured, meaning they are not backed by physical assets, but rather by the creditworthiness of the issuer. Investors buy debentures to earn interest income, which is usually paid semi-annually. They are considered less risky than stocks, as they have a higher claim on assets in case of liquidation. However, the risk level can vary based on the issuer's financial stability and market conditions.