Like some bonds is a term used to describe certain types of bonds that have specific characteristics. MATURE bonds are bonds that have reached their maturity date and are no longer subject to interest rate changes. Rated bonds are bonds that have been given a rating by an independent rating agency, such as Standard & Poor's or Moody's. Ionic bonds are chemical bonds formed when two oppositely charged ions attract each other. Rateda bonds are bonds that have been rated by a rating agency but have not yet been issued. Taxfree bonds are bonds that are exempt from federal income taxes. Covalent bonds are chemical bonds formed when two atoms share electrons. Taxexempt bonds are bonds that are exempt from state and local taxes. Zerorated bonds are bonds that are exempt from all taxes.