In this chapter, we will explore theme engines in general and the default PHPTemplate theme engine in detail.

Our exploration of the PHPTemplate engine lays an important foundation for understanding how to create themes or how to extensively modify existing themes. In the examples below, we show the key files used in the process, and how they impact themes. We also discuss the order of precedence among theme files, and how this principle allows us to override the default template files inside individual themes.

We will also discuss the availability of alternatives to the PHPTemplate engine.

Though you don't need to be fluent in PHP to understand this chapter fully, a little familiarity with the programming language will certainly make things easier. The code examples in this chapter come from the Drupal core and the additional themes Gagarin (installed in Chapter 2) and Zen.