What is a “template” for a web page?
A web page template is just an html document that has all the nested divs, css references – the layout structure – but no content. By saving this document and using it each time you create a new page you keep your site consistent from page to page. By using SSIs for the shared content (navigation, header, footer etc) the template is very small and contains layout instructions only, no content. It would be feasible to create multiple sites with the same template that look completely different. You could have a single template for all your clients, but have a completely different look and feel for each client. You can then hand off this css and template to a client and they can create new pages without knowing anything about html or css. They just add the content.