Facebook has now got a billion active users, it says today. To commemorate the fact, Mark Zuckerberg has posted a letter  up on the firm's blog, thanking the 1,000,000,000 for "giving me and my little team the honor of serving you."
There will be, of course, the inevitable debate over what constitutes an active user : just over half of Facebook's users check the site out every day. If you're a Twitter user and set your FB page to post your tweets, you're seen as an active user - even if you never visit the site.
With a world population of seven billion , the math is extraordinary simple: one in seven people in the world are on Facebook. With just over two and a quarter billion  of these connected to internet, then almost every other person has a Facebook account.
Anyway, just look how Facebook is going to town to celebrate this moment. There's a brand new mission statement.
Phew, those ten digits must have weighing heavily on Zuck's mind for quite some time, because there's quite a lot of thought that's gone into marking the moment. Like this video, which compares Facebook to chairs . And bridges. And great nations. I think I need to lie down, the symbolism of this is all too much. That may or may not be Cameron Diaz doing the voiceover, by the way.I'm just not sure about that chair analogy. Because when I think of a chair, I think of an arse, and I'm not sure that's what Weiden + Kennedy, and the short's director, Alejandro Gonzalez Innaritu, wants us to think. Zuckerberg's letter also included a handy file of fun Facebook factoids, some of which you can see below.
- 1.13 trillion Likes since February 2009.
- 219 billion photos uploaded.
- The average age of a Facebook user is 22.
- The milestone moment occurred at 12.45pm PST on 14 September.
(Actually, we couldn't see them - Kit Eaton and I both reside in Europe, but our lovely NY Editor, Mac, downloaded them for us. So is there some crazy geofencing going on, or did FB fluff the presser?)
[Image via Creative Commons Flickr user James Cridland ]