The audit meta-parameter is the primary change tracking method currently in Puppet. It was introduced in Puppet 2.6, and it provides a way to monitor a resource without enforcing a state on it.

With the introduction of Puppet Enterprise 1.2, Puppet Enterprise gained a compliance dashboard that allowed you to configure and track file changes. This dashboard has since been removed, but it relied heavily on the audit meta-parameter and allowed you to quickly set up auditing.

The audit meta-parameter is a bit of a divergence in the Puppet world. The declarative nature of Puppet is to model the desired state of a resource and allow Puppet to get it there. The audit meta-parameter can allow you to say that you may not care about the state of an item, but you want to know if it changes.