How do annuities work?

{"subtitle":"In exchange for purchasing an annuity, an investor is usually guaranteed to receive something in return. It can either be a fixed rate of return or a fixed payment. Annuity Investing provides flexibility by giving an investor a choice to:","answer":["Invest a lump sum principal or over a period of time","Start receiving payments immediately or at a later date","Select a fixed, variable or an indexed rate of return"]}