What is the difference between PHP require and include?
<p>I know the basic usage of PHP require, require once, include and include once. But I am confused about when I should use them.</p>

<p>Example: I have 3 files, eg: settings.php, database.php, and index.php. </p>

<p>In database.php file, i wrote:</p>

<pre><code>require_once 'settings.php';
</code></pre>

<p>and then in index.php, i wrote:</p>

<pre><code>require_once 'settings.php';
require_once 'database.php';
</code></pre>

<p>so I load settings.php two times, is this okay? Any tips using these functions?</p>
