Annuities are an important part of retirement and investment plans, designed to help your assets grow and provide a steady stream of income when you decide to retire. An annuity is an agreement between you and an insurance company, where you accumulate your funds in a tax advantaged manner and can later receive a series of payments provided by the insurance company for a determined period of time, either a number of years or for life, beginning right away, or in the future, whatever your needs are.