How can PHP code be included in an HTML page for seamless integration?

To include PHP code in an HTML page for seamless integration, you can simply embed the PHP code within `<?php ?>` tags directly within the HTML file. This allows you to mix PHP code with HTML content seamlessly. When the page is loaded on the server, the PHP code will be executed before the HTML is rendered, allowing for dynamic content generation.

&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
    &lt;title&gt;PHP in HTML&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;h1&gt;Welcome, &lt;?php echo &quot;User&quot;; ?&gt;!&lt;/h1&gt;
&lt;/body&gt;
&lt;/html&gt;