Calling Functions in Python: A Beginner’s Guide

Introduction to Calling Functions in Python

Python, a powerful and intuitive programming language, offers a vast library of built-in functions that can perform various tasks, ranging from simple mathematical operations to complex file handling. Understanding how to call these functions is fundamental for any Python programmer, from beginners to the more advanced. This guide aims to demystify the process of calling functions in Python, making it accessible to beginners and serving as a quick refresher for more experienced programmers.

Understanding Python Functions

What is a Function?

A function in Python is a block of organized, reusable code that is used to perform a single, related action. Functions provide better modularity for your application and a high degree of code reusing. Python has a number of built-in functions, such as print(), len(), and type(), but it also allows you to create your own custom functions.

Types of Functions in Python

There are two basic types of functions in Python:

  • Built-in functions: Pre-defined functions that are part of Python’s standard library.
  • User-defined functions: Custom functions that you define yourself to perform a specific task.

How to Call a Function in Python

To call a function in Python, you simply need to type the function name followed by parentheses. If the function requires arguments, you’ll include them within the parentheses. Here’s the basic syntax:


Let’s take the print() function as an example. To print the string Hello, World! to the console, you would call it like this:

print(Hello, World!)

For a function that requires arguments, consider abs(), which returns the absolute value of a number. If you want to find the absolute value of -5, you would call it as follows:


Creating and Calling User-Defined Functions

Defining a Function

To define a custom function in Python, you use the def keyword, followed by the function name, parentheses, and a colon. Inside the parentheses, you can include parameters if your function requires them. The code block within every function starts with a colon (:) and is indented.

def my_function():
    print(This is my first function!)

Calling User-Defined Functions

Once defined, calling your custom function is identical to calling a built-in one:


This call will output: This is my first function!

Parameters and Arguments

When discussing functions, it’s vital to understand the difference between parameters and arguments:

  • Parameters are the variables listed inside the parentheses in the function’s definition.
  • Arguments are the values passed to the function when it is called.

Functions can have multiple parameters, allowing them to receive numerous arguments. Parameters can be positional, or you can use keyword arguments (kwargs), where you specify the name of the parameter you’re passing an argument to, regardless of its position.

Best Practices for Calling Functions in Python

  • Use clear and descriptive names for your functions and parameters to make your code more readable.
  • Include comments and documentation to explain the purpose of the function and how it should be used.
  • Keep your functions focused on a single task for better modularity and reusability.
  • Consider default values for parameters to make your functions more flexible and easier to call.

Useful Resources for Further Learning

  • The Official Python Tutorial is a great place to start for beginners looking to learn more about Python functions.
  • Real Python offers detailed guides and tutorials on a wide range of Python topics, including functions.
  • W3Schools Python Tutorial provides simple and easy-to-understand tutorials for beginners.
  • Stack Overflow is an invaluable resource for finding answers to specific coding questions or problems.

Conclusion and Recommendations

Mastering the art of calling functions in Python is a crucial skill for any aspiring programmer. Whether you’re using Python’s built-in functions or creating your own, understanding how to effectively call functions will significantly improve your code’s efficiency and readability.

For beginners, start with Python’s built-in functions to get a feel for basic syntax and functionality. As you become more comfortable, experiment with creating and calling your own custom functions.

Intermediate users should focus on mastering different types of arguments and parameters, as well as exploring more complex functions like those that return values.

Advanced programmers might delve into more sophisticated topics such as decorators or generators to enrich their Python skills further.


What is the difference between a function and a method in Python?

A function is a block of code that performs a specific task and can be called upon, while a method in Python is similar to a function, but it is associated with an object/class.

Do I always need to define parameters for my functions?

No, parameters are optional. You can define functions without parameters if your function does not require any input to perform its task.

How do I return a value from a function in Python?

To return a value from a function, use the return statement followed by the value or expression you want to return.

Can a Python function return multiple values?

Yes, a Python function can return multiple values by separating them with commas. This effectively returns the values as a tuple.

What is recursion in the context of Python functions?

Recursion occurs when a function calls itself in its definition. It’s a way to solve problems by breaking them down into smaller, more manageable tasks.

We hope this beginner’s guide has shed light on calling functions in Python, making your programming journey easier and more efficient. Should you have any corrections, comments, questions, or wish to share your experiences, please feel free to do so. Engaging with the community not only helps others but also enriches your own understanding and mastery of Python programming.