Comments

Definition

A comment is a non-executable statement or annotation added to code or text to explain, clarify, or document information for human readers. In programming, comments are removed or ignored by the compiler or interpreter when the program runs.

Examples:

In Python, a single-line comment begins with #
In JavaScript, single-line comments begin with //
In many languages, multi-line comments are written using /* ... */

Comments may describe:

the purpose of a code block
the logic behind a solution
warnings or assumptions
temporary notes for future work

Main Content

1. Types of Comments

Single-line comments

: These explain a short idea or a specific line of code. They are usually used for quick notes.
Example: # This variable stores the student name
Example: // Calculate total marks

Multi-line comments

: These are used for longer explanations, such as describing a function, a module, or important logic.
Example:

    """
    This function calculates the average score
    from a list of marks provided by the user.
    """

Documentation comments

: These are structured comments used to generate API or program documentation.
They often describe parameters, return values, and usage.
Example in Java-like languages:

    /**

     * Calculates the square of a number.
     * @param n the number to square
     * @return the square of n
     */

2. Purpose and Importance of Comments

Improves readability

: Comments make code easier to understand, especially when logic is complex or uses unfamiliar concepts.
Example: A loop that processes data may seem confusing without explanation.

Supports maintenance and debugging

: Developers can quickly understand existing code and identify errors or update features safely.
Example: A comment can explain why a special condition exists in an if statement.

Helps teamwork and learning

: In group projects, comments help team members understand each other’s work and help beginners learn faster.
Example: One programmer can explain a function’s role for another team member.

3. Good Commenting Practices

Write comments that add value

: A comment should explain something that is not immediately obvious from the code.
Weak comment: x = x + 1 // increment x
Better comment: // Increase the counter because one record was processed successfully

Keep comments accurate and updated

: Outdated comments are harmful because they can mislead readers.
If code changes, comments should change too.

Use clear and concise language

: Comments should be simple, precise, and easy to read.
Avoid unnecessary long explanations or repeating obvious code.

Avoid over-commenting

: Too many comments can clutter the code and make it harder to read.
Comment important logic, not every single line.

Remove dead or misleading comments

: If a comment no longer matches the code, it should be deleted or corrected.

Working / Process

The programmer writes code and inserts comments at relevant places to explain logic, purpose, or assumptions.
When the program is executed, the compiler or interpreter skips the comments and only processes the actual code.
Other readers, such as teachers, teammates, or future developers, read the comments to understand the code more easily.

How comments work in a program

Program source code
|
|--> Comment lines are read by humans only
|
|--> Compiler/Interpreter ignores comments
|
v
Executable program runs normally

Advantages / Applications

Comments improve understanding of code by explaining difficult sections, making programs easier to read and study.
Comments assist debugging and maintenance because they help identify the purpose of each part of a program.
Comments are used in documentation, tutorials, assignments, and collaborative software projects to communicate clearly with others.

Summary

Comments are notes added for human understanding and are ignored by the computer.
They are used to explain code, improve readability, and support maintenance.
Comments should be clear, correct, and useful.
Important terms to remember: comment, single-line comment, multi-line comment, documentation comment, readability, maintenance