Prohibiting direct web access to important Joomla files by placing them outside your public_html directory is a good practice in terms of security.

For example, if you want to move the main configuration file (configuration.php) of your Joomla outside the public_html directory, you can do that by following these instructions: 

• Move the configuration.php file to a safe directory outside of public_html and rename it however you want. For the purpose of this article we have chosen to name the file joomconf.original.php
• Create a new configuration.php file in your public_html directory containing only the following code

<?php
require( dirname( __FILE__ ) . '/../joomconf.original.php ' );

?>