What is owed by one party to another. Debts usually come with interest, so that the amount that must be paid back grows over time, and with a date by which the debt must be repaid in full.
Companies and governments use debt to finance their operations. One way they do this is by issuing bonds, also known as debt securities. Bonds amount to a loan from the bondholder to the issuer with an agreed rate of interest and a date by which the principal must be repaid.