How can white spaces behind the closing PHP tag in included files cause issues in PHP scripts?

Having white spaces behind the closing PHP tag in included files can cause issues in PHP scripts because it can inadvertently send extra whitespace characters to the output buffer, leading to "headers already sent" errors or other unexpected behavior. To solve this issue, make sure to remove any white spaces or new lines after the closing PHP tag in included files.

<?php
include 'included_file.php'; // Make sure there are no white spaces after the closing PHP tag in included_file.php
?>