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Comments in Python

Lines in your code that Python never runs — written for humans, to explain intent, leave notes, or switch off code while debugging.

Overview

This topic covers how to write comments in Python. Comments are lines in code that are not executed by the Python interpreter — they exist purely for humans to read, to explain what the code does, add notes, or temporarily disable code.

Key Concepts

A comment starts with the hash symbol (#).
Everything after # on that line is ignored by Python.
Comments are used to improve code readability and collaboration.

Syntax

# comments

A bare comment — just marks that comments are being demonstrated.

# this is a comment

A descriptive single-line comment explaining code or intent.

An empty comment (just a # with nothing after it) — technically valid but has no content.

Important Points

Comments in Python are written using single-line comments only with # (Python does not have a dedicated multi-line comment symbol like /* */ in other languages).
Anything written after # on the same line is not executed.
Comments are commonly used to:
- Explain why a piece of code exists
- Temporarily disable/"comment out" a line of code during debugging
- Improve readability for other developers (or your future self)

Things to Remember

# = start of a comment in Python.
Comments are for humans, not the interpreter — they don't affect program execution.
Good practice: write comments that explain why, not just what (the code itself usually shows what).

Quick Revision

In Python, anything after # on a line is a comment and is ignored during execution. Comments help explain code, make it more readable, and can be used to disable a line temporarily while testing. Python only supports single-line comments natively.