Tags and Includes – A Lesson on Proper HTML Structure Embedding within PHP

Often in PHP you find simple sites structured as follows

index.php

<?php
$title = 'page title';
$description = 'desc';
$keywords = 'keywords';
include('includes/header.inc.php');
?>
Our Page Content
<?php include('includes/footer.inc.php'); ?>

includes/header.inc.php

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<title><?= $title ?></title>
	<meta name="description" content="<?= $description ?>" />

	<meta name="keywords" content="<?php
	if(empty($keywords)){
		echo 'Default Keywords';
	}else{
		echo $keywords;
	} ?>" />
	<link href="css/style.css" rel="stylesheet" type="text/css" />
	<link href="css/print.css" rel="stylesheet" type="text/css" media="print" /> 
</head>
<body>
	<div id="page_wrap">
		<div id="header" >
			<a href="index.php"><img src="images/logo.jpg" border="0" /></a>
		</div>

Whereas