What is the proper way to include code from an external file in ASP.NET?
<p>I've been using PHP for years to build websites.  Often I will use an include to bring in, say a navigation menu:</p>

<pre><code>&lt;?php include 'includes/nav.php'; ?&gt;
</code></pre>

<p>I am much more of a novice when it comes to ASP.NET (C#).  I am wondering what is the correct (and most efficient) way of doing the equivalent of a PHP include, in ASP.NET?</p>
