In PHP, comments are used to include explanatory or informative notes within the code that are ignored by the interpreter during execution. Comments help make the code more readable and understandable for both the developers who write it and others who may need to review or maintain it. There are two main types of comments in PHP: single-line comments and multi-line comments.

1. Single-Line Comments:

Single-line comments are used for adding comments that span only one line. They are useful for adding brief explanations to specific lines of code.

php
// This is a single-line comment
$variable = 42; // Assigning a value to the variable

2. Multi-Line Comments:

Multi-line comments are used when you need to write comments that span multiple lines. They are often used to provide more detailed explanations of code blocks or to temporarily disable portions of code.

php
/*
This is a multi-line comment.
It can span multiple lines and is enclosed between
the opening /* and closing */ symbols.
*/
$result = performComplexCalculation($input); // Commenting out this line for now

3. Doc Comments (Documentation Comments):

PHP also supports a specific style of comments called "doc comments" or "documentation comments." These comments are often used to generate documentation automatically using tools like PHPDoc.

php
/**
* This function calculates the square of a number.
*
* @param int $number The input number.
* @return int The square of the input number.
*/
function calculateSquare($number) {
    return $number * $number;
}

Comments should be used judiciously to provide context, explanations, or warnings in your code. Overuse of comments or comments that state the obvious may clutter the code and reduce its readability. Well-placed and informative comments, however, can greatly enhance the understanding of complex logic or algorithms.

Remember that comments are ignored by the PHP interpreter and have no impact on the execution of your code. They are purely for human consumption and are meant to assist developers in understanding the codebase.

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