Python Comments

Comments are annotations in your code that are ignored by the Python interpreter. They allow you to add notes or explanations for yourself or others who may read your code. Using comments properly can make your code more understandable, especially when working on larger projects.

What You'll Learn

In this guide, you'll learn about the different types of comments in Python and best practices for using them.

Why Use Comments?

  • Code Explanation: Comments help explain what your code is doing, making it easier for others to understand.
  • Debugging: Temporarily disable code to test or debug your program.
  • Collaboration: Comments allow multiple developers to understand the code easily.

Types of Comments in Python

1. Single-Line Comments

Single-line comments are used to add a comment on a single line. They begin with a hash symbol # and continue to the end of the line.

python
# This is a single-line comment
print("Hello, world!")  # This prints a message

How It Works:

  • #: Used for single-line comments. Python ignores everything after the # symbol on that line.
  • print("Hello, World!"): This line of code will be executed and will print the message to the screen.

Output

Hello, World!

2. Multi-Line Comments

Multi-line comments are used for longer explanations or to comment out blocks of code. In Python, multi-line comments are typically written as docstrings, which are enclosed in triple quotes ''' or """.

python
"""
This is a multi-line comment.
It can span multiple lines.
"""
print("Hello, world!")

How It Works:

  • ''' ''': This is the syntax for a multi-line comment. Python ignores everything within these triple quotes.
  • print("Hello, world!"): This line of code will execute as expected.

Output

Hello, world!

Note: Python doesn't have official multi-line comment syntax. Triple-quoted strings are often used like comments but are actually string literals unless used as docstrings.

Exercises

Try the following exercises to practice working with comments in Python.

1. Write a program that prints your name and includes a comment explaining what the code does.
python
# Print your name
print("Your Name")
2. Write a program that includes a multi-line comment describing the purpose of the program.
python
'''
This program prints a welcome message to the user.
It demonstrates how to use Python's print() function.
'''
print("Welcome to Python!")
3. Write a program that temporarily disables a line of code using a comment and runs the remaining code.
python
# print("This line is disabled.")
print("This line is executed.")

*Tip: After completing an exercise, try experimenting with comments to explore their usage further!

Frequently Asked Questions

What are comments in Python?

Comments in Python are non-executable lines in your code, used to annotate or explain the code to the reader. Python ignores everything after the # symbol in single-line comments, and everything inside triple quotes ''' ''' or """ """ for multi-line comments.

Why are comments important in Python?

Comments improve code readability, making it easier to understand the logic. They also help when debugging, documenting, and collaborating with other developers.

How do I write a single-line comment in Python?

A single-line comment starts with the # symbol. Everything after # on that line will be ignored by Python.
Example: # This is a single-line comment

What is the difference between a comment and a docstring in Python?

Comments are used to annotate code and are ignored by Python. Docstrings, on the other hand, are used to describe functions, classes, or modules and are stored as part of the program. They are typically enclosed in triple quotes (''' ''' or """ """).

Can I use comments to disable code in Python?

Yes! You can temporarily disable a line of code by commenting it out. For example, to disable a line that prints text, you can write # print("This line is disabled.").

Can I write multi-line comments in Python?

Yes, multi-line comments in Python are typically written using docstrings. You can use triple quotes ''' ''' or """ """ to span comments across multiple lines.
Example:
'''\nThis is a multi-line comment.\nIt can span across multiple lines.\n'''

Are comments required in Python?

No, comments are not required for your code to run in Python. However, they are highly recommended for improving code readability and maintainability, especially when working on larger projects or with other developers.

What's Next?

Next, you'll learn about Indentation in Python. Indentation is essential in Python to define code blocks like loops and functions. Unlike other languages, Python uses indentation to determine the structure of the code, making it crucial for writing error-free programs.