And this is the challenge for Google. If mobile users reliably go to Facebook daily, that is where people will want to advertise to them, if they are spending all of their time on their mobile rather than their laptop or desktop, then mobile advertising will be more important than advertising in the laptop/desktop space.

Interesting times.

Doubtful. People go to search engines to buy things. People go to Facebook to hang out. FB ads are unlikely to supplant Google for that reason.

It doesn't matter whether an advertiser wants to advertise on a certain platform. If nobody clicks on the ad, then that advertising is useless. Maybe they just want to put their brand into the viewer's head rather than have the viewer click on the ad. That's a valid strategy, but not really what most advertisers pay for.

In fairness Google announced the same figure for Android recently, so they're not completely losing control over mobile at the moment.

I agree with you, the insight is that the most common thing people do on laptops or desktops is 'search for something' if the most common thing people do on mobile is 'check my facebook' then that puts Facebook on mobile in the seat where Google sits on computers. I'm bummed I sold my FB stock when it hit 40.

Could they be reporting monthly active 'devices' as 'users'?

More clearly, could one user on an iPad and Android phone count as two different 'active users'?

They definitely measure those numbers separately.

Is there a universally agreed metric of what a mobile MAU constitutes?

Is there a generally agreed unit of time spent per instance of log in activity, to qualify as a MAU?

Or just the very act of stumbling into the FB app (somehow), through the myriad ways possible out there, still constitute a MAU?

I understand that this does not count (?) API calls (justifiably).

All these years in, I just want to assure myself that we are still not in the era of sketchy metrics and non-standard parameters. Thats all.

I was also wondering this. Facebook has embedded widgets on perhaps more third party sites than any other platform. Does that mean that, while logged in, loading up Facebook comments on a blog post counts you as an active user? Loading an embedded Like button?