A "debt instrument" is a financial tool used to acquire capital, which has to be repaid with interest over time. This type of instrument can take many forms, including bonds, notes, bills, and loans. Other synonyms for debt instruments may include debt securities, credit securities, fixed-income securities, or debt obligations. Each of these synonyms carries the same implication for the borrower: a legal obligation to pay back the borrowed funds, plus interest. Debt instruments are common in finance and used by corporations, governments, and individuals to finance various projects or expenses. Regardless of the name, debt instruments are essential tools in the world of finance.