Comments

Comments

In this tutorial, we'll write comments that clarify the why behind your code.

Comments are notes in your code that Python ignores. They are for humans.

# This is a comment
print("This line runs")

The comment does not run. It helps explain the code.

Why Comments Exist

Code explains what happens. Comments should usually explain why something happens.

Good comment:

# Discount applies only during the summer sale
discount = 0.20

Less useful comment:

# Set discount to 0.20
discount = 0.20

The second comment repeats the code. The first comment adds context.

Inline Comments

You can place a comment after code:

total = price * 1.2  # Add 20% tax

Use inline comments sparingly. If a line becomes crowded, put the comment above the code instead.

Temporarily Disabling Code

Beginners often use comments to temporarily stop a line from running:

print("This runs")
# print("This does not run")

This is useful while testing, but remember to clean up old commented-out code later.

Multi-Line Notes

Python does not have a special multi-line comment syntax. You will sometimes see triple-quoted strings used as notes:

"""
This note spans several lines.
Python treats it as a string.
"""

For now, prefer # comments unless you have a specific reason.

Practice

Write a short program that calculates the cost of three tickets. Add comments explaining the price and the final calculation.