Debentures are a type of long-term debt instrument issued by corporations, governments, or financial institutions to raise funds from investors. They represent a form of borrowing for the issuer and serve as a promise to repay the principal amount along with periodic interest payments to the debenture holders.

Unlike traditional bank loans, debentures are not secured by specific assets or collateral. Instead, they are backed by the general creditworthiness and reputation of the issuer. Debenture holders are considered unsecured creditors and have a claim on the issuer's assets in case of default, but their claims are subordinate to secured creditors and bondholders.

Debentures can have various features and terms, such as fixed or floating interest rates, maturity dates, and conversion options. They are typically issued with a predetermined maturity period, ranging from a few years to several decades. Interest payments are made periodically, usually semi-annually or annually, and the principal amount is repaid at maturity.

Investors are attracted to debentures because they offer a fixed income stream and can be traded in the secondary market. For issuers, debentures provide an alternative source of long-term financing and help diversify their funding base.

It's important to note that the specific terms and characteristics of debentures can vary depending on the issuer and the regulatory environment in which they are issued.