If your site in php you can write something like this:
Index.php
<?php
include 'header.php';
?>
<div class="container">
Text
</div>
<?php
include 'footer.php';
?>
Header.php
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Title</title>
<meta name="description" content="">
<meta name="keywords" content="keywords">
<link rel="stylesheet" href="css/style.css">
<script src="js/custom.js"></script>
<link rel="shortcut icon" href="img/favicon.ico">
<!--[if lt IE 9]>
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
</head>
<body>
<header>
</header>
Footer.php
<footer>
</footer>
</body>
</html>