Wombat uses patTemplate (version 3) as template engine to generate HTML output. patTemplate is free and easy to use template engine. There is a bunch of examples at http://examples.php-tools.net that show both how to write template files and use them from PHP-side.
<patTemplate:tmpl name="snippet"> (MAIN) </patTemplate:tmpl>
There is one major template file for each site. Which file to use can be configured with the skin/tmpl-tag in site.xml. Usually named "site.tmpl" and locate in BASEDIR/template/site.tmpl
One big feature of patTemplate are template variable modifiers. patTemplate comes with a bunch of generic modifiers (see ) that makes it very easy to format unix-timestamp human readable etc. Besides Wombat brings additional modifiers, those are general purpose modfiers as well, still, they only make sense in a Wombat-Environment.