"We define a mobile DAU as a user who accessed Facebook via a mobile application or via mobile versions of our website such as m.facebook.com, whether on a mobile phone or tablet, or used our Messenger mobile application (and is also a registered Facebook user) on a given day. The numbers for mobile DAUs do not include Instagram, WhatsApp, or Oculus users unless they would otherwise qualify as such users, respectively, based on their other activities on Facebook."

What does that mean?

Why did they use the word "accessed" vs "authenticated"? Did the user leave a tab on their cell phone open after they logged into facebook?

Many users log in once and forget to logout... Does that continue to present itself as someone accessing facebook?

How many users access via the app? via the mobile web page?

If you take out people who used Messenger app what would this number be? Also, can I be a Messenger user and not a registered Facebook user?

Pay attention to the footnotes. It shows up on many pages of the presentation.

I would prefer knowing how many logged in each day. How many did something purposefully like look at a friends timeline, search a friend, look at possible friends. How many posted a comment, did a "like", clicked on an ad...