A layout is a simple HTML::Template file which contains place-holders for your
content to go into. The most basic layout would look like this:
<html>
<head>
<title><!-- tmpl_var name='title' escape='html' --></title>
</head>
<body>
<!-- tmpl_var name='content' -->
</body>
</html>
Templer will insert the contents of each page into the region named "content", and
in this example we've assumed that each page will define the variable "title". Together the content and the title complete the page.
You can be significantly more sophisticated than just replacing the content and the title of the output page though - by including optional components as we've done with this example.