Smarty is a template engine for PHP, facilitating the separation of presentation (HTML/CSS) from application logic. This implies that PHP code is application logic, and is separated from the presentation.
The PHP programming language is great for code development but when mixed with HTML, the syntax of PHP statements can be a mess to manage. Smarty makes up for this by insulating PHP from the presentation with a much simpler tag-based syntax. The tags reveal application content, enforcing a clean separation from PHP (application) code. No PHP knowledge is required to manage Smarty templates.
Smarty is used within an OSF installation to simplify the creation of data presentation formats in tabular or structured form.