 Annuities can be purchased to provide an income during retirement, or originate from a "structured settlement" of a personal injury lawsuit.Life annuities may be sold in exchange for the immediate payment of a lump sum (single-payment annuity) or a series of regular payments (flexible payment annuity), prior to the onset of the annuity.The payment stream from the issuer to the annuitant has an unknown duration based principally upon the date of death of the annuitant.