What is the use of the @ symbol in PHP?

The at sign (@) is used as error control operator in PHP. When an expression is prepended with the @ sign, error messages that might be generated by that expression will be ignored. If the track_errors feature is enabled, an error message generated by the expression and it will be saved in the variable $php_errormsg. This variable will be overwritten on each error.

Program 1:

<?php

// File error
$file_name = @file ('non_existent_file') or
    die ("Failed in opening the file: error: '$errormsg'");

// It is used for expression
$value = @$cache[$key];

// It will not display notice if the index $key doesn't exist.

?>

RunTime Error:

PHP Notice:  Undefined variable: errormsg in /home/fe74424b34d1adf15aa38a0746a79bed.php on line 5

Output:

Failed in opening the file: error: ''

Program 2:

<?php

// Statement 1
$result= $hello['123']

// Statement 2
$result= @$hello['123']
?>

It will execute only statement 1 and display the notice message

PHP Notice:  Undefined variable: hello.

Note: The use of @ is very bad programming practice as it does not make error disappear, it just hides them, and it makes debugging a lot worse since we can’t see what’s actually wrong with our code.

References: Error Control Operators