The role of templates in Drupal

We may have heard the term template before when talking to someone about theming, but what exactly is a template? We can think of a template as a text file no different from any HTML document that provides a method for separating the presentation layer from the business logic.

In traditional PHP websites, we can mix PHP with HTML and CSS, which makes managing web pages both difficult and dangerous. Drupal provides us with the ability to use templating engines to enforce the separation of the two, so we can begin to focus more on the HTML and CSS and worry less about the PHP.

How templates work

In general, templates can contain HTML markup and PHP variables that output content contained within a Drupal database. Templates can be as small as a few lines of HTML that hold the presentational layer for a block that is displayed in a region on the page, or the actual page itself, with containers defined for header, content, and so on:

If we break down the image into...