Variables are names

Like slope formula above, you can put y1-y2 or y2-y1. Variables are just names in programming (and math).

Let's start with an example.

number1 = 2

I just created a variable called number1

Python is dynamics

In Python, variables and data are in open relationship. No commitment!
The same variable can be used over and over by different type of data (integers, string, images, etc).

variable. when?

Almost always.
Variables are shorthand notation to develop programs. Imagine you have to write your math formula 100000 times. WOW

y = x**4 + x**3 + 2*(x-2)**3 + 10000
print y
z = 2*y + 3*x**2
w = z + y + z + x
print 'your result of w is:', w

the variables x, y, z, w are reusable in this code :)

read that