In Python, functions are highly flexible—one of the features that makes them so is the ability to use default arguments and keyword arguments. These features allow you to call functions more efficiently, reduce errors, and write cleaner code.

This guide will walk you through the concepts of default and keyword arguments, how they work, and how to use them effectively with practical examples.

1. Default Arguments in Python

Default arguments allow you to assign a default value to a parameter in a function definition. If a value is not provided for that parameter during the function call, the default is used.

# Example 1: Default argument
def greet(name="Guest"):
    print(f"Hello, {name}!")

greet()            # Output: Hello, Guest!
greet("Anjali")    # Output: Hello, Anjali!

Benefits of Default Arguments

• Reduces the need for overloaded functions
• Makes functions easier to use
• Improves code readability and flexibility

2. Keyword Arguments in Python

Keyword arguments allow you to specify arguments using the parameter names. This way, you can pass arguments in any order.

# Example 2: Using keyword arguments
def describe_pet(pet_name, animal_type):
    print(f"I have a {animal_type} named {pet_name}.")

describe_pet(animal_type="dog", pet_name="Bruno")

Here, even though the arguments are passed in a different order, the function still works correctly because the keywords match the parameter names.

3. Combining Default and Keyword Arguments

You can use default values and keyword arguments together for even more flexibility.

# Example 3: Combining both
def book_flight(source, destination="Delhi", seat_type="Economy"):
    print(f"Flight booked from {source} to {destination} in {seat_type} class.")

book_flight("Mumbai")  # Output: Flight booked from Mumbai to Delhi in Economy class.
book_flight("Chennai", seat_type="Business")

4. Order of Arguments Matters

When defining a function, positional parameters must come before default parameters.

# Correct way
def user_info(name, age=25):
    print(f"{name} is {age} years old.")

# Incorrect way (raises SyntaxError)
# def user_info(age=25, name):  ❌

5. Keyword Arguments Improve Clarity

Using keyword arguments makes function calls more readable, especially when dealing with multiple parameters.

# Example 4: Readable with keywords
def create_account(name, email, role="user"):
    print(f"Account created for {name} ({email}), role: {role}")

create_account(name="Reena", email="reena@example.com", role="admin")

6. Function Call Flexibility

With keyword arguments, you can skip optional values and only override what you need.

# Example 5: Skipping to the keyword argument
def send_email(to, subject="No Subject", body="Empty"):
    print(f"Sending to: {to}\nSubject: {subject}\nBody: {body}")

send_email("hello@example.com", body="This is a test email.")

7. Summary Table

8. Final Thoughts

Default and keyword arguments add flexibility and clarity to your functions. They reduce the need for repetitive code and allow functions to be reused in a wide range of scenarios. By mastering these, you can write Python functions that are not just powerful, but also easier to understand and maintain.