What is an annuity? What is the difference between a fixed annuity and a variable annuity? What

Question:

What is an What is the difference between a fixed and a variable What is the main disadvantage of annuities?
Annuity
An annuity is a series of equal payment made at equal intervals during a period of time. In other words annuity is a contract between insurer and insurance company in which insurer make a lump-sum payment or a series of payment and, in return,...