An annuity is a contract in which an insurance company makes a series of payments. There are two primary types of annuities, immediate and deferred. In an immediate annuity, once you purchase it, you create a stream of income and begin getting paid. In a deferred annuity, once you purchase it, you let it grow (the accumulation period) and receive income at a later date. Often, the type of annuity you choose depends on what stage of life you are in.