Variable Scope

A variable is only available from inside the region it is created. This is called scope.

def myfunc():
  x = 300
  print(x)
 
myfunc() # This will print 300
print(x) # While this will cause an error

In Python, Variables that are created outside of a function (as in all of the examples above) are known as global Variables. Global Variables can be used by everyone, both inside of functions and outside.

x = 300
 
def myfunc():
  print(x)
 
myfunc() # This will print 300
print(x) # And this will also print 300

If you create a variable with the same name inside a function, this variable will be local, and can only be used inside the function. The global variable with the same name will remain as it was, global and with the original value.

x = 300
 
def myfunc():
  x = 200
  print(x)
 
myfunc() # This will print 200
print(x) # While this will print 300

The global keyword makes the variable global.

def myfunc():
  global x
  x = 300
 
myfunc() # This will print 300
print(x) # And this will also print 300

Note: This is not recommended, as it can cause confusion and lead to bugs.