Best way to find out what anything is: Google.
Type 'define:Smarty' (without the quotes) into a Google search box and get this page: Google definition of smarty with links

In short, Smarty is a web template system written in PHP. Smarty separates PHP, as a business logic, from HTML, a presentation logic, and generates web content by the placement of special Smarty tags within a document (i.e. variable substitution).

I have never used it though.

__________________
-- Bill
"Why is it drug addicts and computer aficionados are both called users?" -Clifford Stoll