This tells Smarty whether or not to cache the output of the templates to the $cache_dir. By default this is set to the constant Smarty::CACHING_OFF. If your templates consistently generate the same content, it is advisable to turn on $caching, as this may result in significant performance gains.

You can also have multiple caches for the same template.

See also $cache_dir, $cache_lifetime, $cache_modified_check, is_cached() and the caching section.