To ensure effective implementation and sustenance of management system, Audit is the most basic and yet important tool. Environmental audit is a general term that can reflect various types of evaluations intended to identify environmental compliance and management system implementation gaps, along with related corrective actions.
In this way they perform an analogous (similar) function to financial audits.
There are generally two different types of environmental audits: compliance audits and management systems audits. Compliance audits tend to be the primary type in the US or within US-based multinationals.