An annuity is a contract between you (the annuity owner) and an insurance company. In return for your payment, the insurance company agrees to provide either a regular stream of income, the right to withdraw up to a certain percentage per year, or even a lump sum payment at some future time (generally, once you retire or pass age 59 1/2).
For some, annuities can complement a total retirement income strategy to supplement other sources of money during retirement. Annuities have advantages such as allowing you to pay in unlimited premiums and they grow compound tax-deferred. (Upon withdrawals,** you will pay taxes on interest earned and the principal if the annuity was purchased with pre-tax dollars.) However, annuities are not for everyone.