Why do you think we need layout.html file and how would the header be re-used? code example
Example 1: html layout
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<h1>This is a Heading</h1>
<p>This is a paragraph.</p>
</body>
</html>
Example 2: html layout
<!DOCTYPE html> <!-- Start of coding page -->
<html> <!-- Start of html coding -->
<head> <!-- Start of head -->
<title>TITLE</title> <!-- Title -->
<script>
//JavaScript
</script>
<style>
/* CSS */
</style>
</head> <!-- End of head -->
<body> <!-- Start of body -->
<h1>Hello!</h1>
</body> <!-- End of body -->
</html> <!-- End of html coding -->