Alerts let you configure some pre-defined actions that will generate an email to you alerting to you of what is going on. One example is a reminder when the server isn't up to date for a new release of CrushFTP. Or a notice when a drive is getting low on disk space, or anytime a user changes their password or gets low on quota space...you want to know.

Alerts are global, where the user events are specific to a particular user and event type.