Debentures are debt instruments issued by companies, deriving from the Latin 'debere,' and serve as loan certificates with specific redemption dates and fixed interest rates. They come with various features, including no voting rights for holders and being prioritized in repayment during bankruptcy, with classifications based on security, convertibility, permanence, negotiability, and priority. Pros include regular interest payments and potential conversion to equity, while cons encompass risks related to interest rate fluctuations, creditworthiness, and inflation.