Please help me, in simple terms, understand the "def" function.

I know how to use functions and how to create the calculator program by my self, but I don't understand the function of "def".

The def function is something that creates a function,
which is something that repeats an action over and over again.
A function can have parameters:

Code:


def print2(var):
    print var

def add(x, y):
    print x + y

hello = 'Hello!'
add(1, 2) #3
print2(hello) #Hello!