What’s In a WordPress Theme?
When you look at a webpage, you see it as one page, with various elements (masthead, footer, content area, sidebar, etc.), and in straight html, you code it as one page, with the DOCTYPE declaration at the top, opening and closing tags for various parts of the page. With themes, though, these parts are divvied up and each one becomes their own page, functioning under a model similar to the Model View Controller.