The idea of variables refers to something that can change in the course of a program. A vairable can be very useful in a program because it allows the input of users and can change the value of their input. It can be altered by operands and operators and essentially allows the program to run in the first place. Variables in computer terms are much like they are in math terms in the since that they can be changed and represented and altered. They are not always representing numbers either; they can represent other values set equal to words as well. Variables are the keystone of programming