Are placeholders like %title a standard feature in PHP or just developer-defined?

Placeholders like %title are not a standard feature in PHP, but rather a convention often used by developers to indicate where dynamic content should be inserted. To implement placeholders in PHP, you can use sprintf() function which allows you to format a string with placeholders and then replace them with actual values.

$title = "Hello, World!";
$message = sprintf("This is the %s", $title);
echo $message;