What are the implications of using different character encodings in PHP files, especially when including HTML forms?

When using different character encodings in PHP files, especially when including HTML forms, it can lead to issues with displaying special characters correctly or processing form data accurately. To ensure compatibility and consistency, it's important to use the same character encoding throughout your PHP files and HTML forms. You can specify the character encoding in your PHP files using the header() function with the "Content-Type" parameter set to the desired encoding, such as UTF-8.

<?php
header('Content-Type: text/html; charset=UTF-8');
?>