Comments

If you want to write your code just to explain a block of code or to avoid the execution of a specific part of code while testing, then python comments comes in handy.

Single-line comment

To write a single-line comment just add a # at the start of the line.

# This is a single-line comment
print("Hello World!")

Python single line comments

As you can see in the terminal, the line starting with # is ignored by the Python interpreter and not printed. It’s there only for understanding.

Tip: Most code editors, including VS Code, let you toggle a comment with a keyboard shortcut (Ctrl+/ on Windows/Linux, Cmd+/ on Mac).

Toggle comments in VSCode

Multi-Line Comment

In Python, there are two ways to write multi-line comments:

Using # on each line:

You can write comments over multiple lines by starting each line with the # symbol.
```
# This is a comment
# that spans multiple
# lines
print("Hello, World!")
```
Using a multi-line string (triple quotes):**

While multi-line strings (triple quotes: """ or ''') are typically used for docstrings (documentation strings), they can also be used to create multi-line comments, as Python will ignore them if they’re not assigned to a variable or used in any other way.
```
"""
This is a multi-line comment
using a string.
Python will ignore this string.
"""
print("Hello, World!")
```
Note: This works, but it isn't a true comment. Python evaluates the string and throws it away. If you place a string like this as the very first line inside a function or class, Python treats it as a docstring instead, which serves a different purpose. Stick to # for real comments.

Now, let’s look at some best practices to keep in mind while writing comments.

Best Practices for Comments

Use comments to explain "why" rather than "what":

Use comments to explain the reasoning behind your code, especially for more complex sections.

# Using a while loop because we need to repeat the task until the condition is met
while counter < 10:
    counter += 1

Avoid over-commenting:

Don't add comments for every single line of code. Your code itself should be as readable as possible.

# Bad practice
counter = 10  # Set counter to 10
result = counter * 2  # Multiply counter by 2

Instead, just write clear code:

counter = 10
result = counter * 2  # This line is already clear

Keep comments updated:

A comment that no longer matches the code is worse than no comment at all.

👉 Next tutorial: Python Print Function