Scope refers to the availability of a variable. Typically, a variable created inside a function is only available from within that function. This is called local scope.

A variable created inside a function belongs to the local scope of that function, and can only be used inside that function.

def myFunction():
    x = "Hello World"
    print(x)

myFunction()

Output:

Hello World

A variable created in the main body of the Python code is a global variable and is available from within any scope, global and local.

x = "Hello World"

def myFunction():
    print(x) #refer to the global variable from within a function

myFunction()
print(x) #refer to the global variable outside of any functions

Output:

Hello World
Hello World

If there are variables with the same name inside and outside of a function, Python will treat them as two separate variables – one global and one local depending on where they are created.

x = 88 #x is global

def myFunction():
    x = 44 #x is local to the function
    print(x)

myFunction()
print(x)

Output:

44
88

To create or modify a global variable while in the local scope, the global keyword is used.

Example (creating a global variable locally):

def myFunction():
    global x
    x = 44

myFunction()
print(x)

Output:

44

The global keyword can also be used to make a change to a global variable inside a function.

Example (changing a global variable locally):

x = 44 #x is global

def myFunction():
    global x #make x within the function global so that the value can be changed globally
    x = 88

myFunction()
print(x) #though printed outside the function, the value has been updated

Output:

88

The nonlocal keyword is used to work with variables inside nested functions, making the variable belong to the outer function.

def myFunction1():
    x = 44
    def myFunction2():
        nonlocal x #makes "x" belong to myFunction1
        x = 88
    myFunction2()
    return x

print(myFunction1())

Output:

88

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