Checks all your Magento Files, and will tell you if Core files have been altered, Core files have been overridden, Original files have been altered, added files, Core Modules installed, Community Modules installed and local modules installed. This allows you to audit your Magento install for any poor coding practices such as altering core files, and it also allows for a general code audit for security purposes. Don't think your Magento install is correct and safe, know it is!
