Global Variables

A global variable is a variable defined outside of any function, making it accessible from anywhere in the program, including from within functions.

Global vs Local Variables

A variable created inside a function is called a local variable and only exists while that function is running. A variable created outside all functions, at the top level of a script, is a global variable and remains accessible throughout the program's execution.

course_name = "Data Science"   # global variable

def show_course():
    print("Course:", course_name)   # can read the global variable

show_course()

Reading vs Modifying Global Variables

A function can freely read a global variable's value without any special syntax. However, if you try to modify a global variable's value inside a function without additional steps, Python will treat it as a new local variable instead.

Coming Up Next

Next, you'll learn exactly how the global keyword allows a function to modify a global variable's value directly.