Debt securities are instruments that represent a lender's right to receive repayment of an amount borrowed by the issuer, plus interest. The most common types of debt securities are bonds and notes. However, there are several other synonyms for debt securities, like fixed income securities, fixed payment securities, income securities, interest bearing securities, debt obligations, and bonds. These synonyms generally refer to the same thing; an investment that generates regular interest payments until it matures, at which time the investor receives the original principal amount back. Debt securities are an important part of the financial market, providing investors with a way to earn a reliable income stream from their investments.