just like the plugin builder is not conventional. I invite you to turn this code into a html file and open it in all of your browsers. you will find that even good old Microsoft Word displays the mark up correctly.
<html>
<head>
<body>
<h1>Hello World</h1>
</body>
<title>Page Title</title>
</head>
<body>
<p>The content of the body element is displayed in the browser window.</p>
<p>The content of the title element is displayed in the browser tab, in favorites and in search engine results.</p>
</body>
</html>