Debt securities are financial instruments that represent a loan made by an investor to a borrower, typically a corporation or government. These securities include bonds, notes, and debentures, which promise to pay back the principal amount along with interest over a specified period. Investors purchase debt securities to earn interest income and to diversify their investment portfolios. The risk associated with these securities varies based on the issuer's creditworthiness, with government bonds generally considered safer than corporate bonds. Understanding the nuances of debt securities can help investors make informed decisions in the financial markets.