Smarty is a PHP template engine aimed at purifying presentation (HTML/CSS) from application logic so that designers and developers can work together with less friction.

It uses a tag-based syntax (e.g. {$variable|modifier}) so designers don’t need to dive into heavy PHP code to change appearance, while developers retain control over the underlying logic. It supports caching, template compilation, and a plugin architecture, making it suitable for larger projects.

One of Smarty’s strengths is its maturity and widespread use - you’ll find it in many PHP projects - but it has also faced criticism: some argue the template engine can feel heavy in a modern context and that simpler or more native PHP solutions may suffice. If you have a project where you want a clear separation of templates from code, and perhaps designers who should not touch backend logic, Smarty can be an excellent choice.