When Facebook changed the metrics it reports for application several months back, Monthly Active Users (“MAU”) became the primary public application metric. However as several developers on the forums have been asking lately, the meaning of MAU is not exactly clear to the developer community. However, given new responses from the Facebook Platform Team on the Developer Forums, a concrete definition is now known.

MAU – Monthly Active Users

Simply put, MAU refers to the number of unique users per the past 30 days. This metric is most prominently displayed on application about pages, and is sometimes confused for the Unique Canvas Page Views metric, as they are typically closely related.

To see the active user breakdown for your application by day, jump to your application Insight’s page and select “Active Users (Engagement)” from the dropdown menu on the Usage tab. You will see your unique daily active users per day. To see your application’s current MAU value, check the “Past 30 days” box.

What is a “Unique” user?

Another frequent question is how users are tallied. According to the Facebook Platform Team, a unique user can be generated from any of the following actions:

• mock ajax request
• fbml link click
• canvas page view
• click-to-play swf
• message attachment
• fbjs ajax
• accepting a request
• viewing a profile tab
• publishing something via a publisher

In addition, the user must at least be logged into Facebook and accessing your application to be counted as active. However, the user does not need to have already authorized your application to be counted. Note that there is no way to distinguish between a user logged out of Facebook and a user who hasn’t authorized your application.

Metrics are essentially the vital-signs of an application, important to both analysts and developers as ways to monitor the success and growth of applications. Keeping a firm understanding of these underlying metrics is key to success on the platform.