About 25% of the world's population is now logging into Facebook (NASDAQ:FB) at least once a month. Crossing 2 billion monthly active users (MAUs) should come as no surprise, as Facebook was already on the threshold at the end of the first quarter, when it had 1.94 billion MAUs. Of those, 1.2 billion were daily active users (DAUs)

CEO Mark Zuckerberg shared the milestone on Facebook earlier today:

Facebook's scale is unprecedented and unparalleled

It's hard to overstate how incredible Facebook's scale is. Reaching such a critical mass of users is Facebook's most important advantage over rivals, which continue to struggle growing their own respective user bases despite being but a fraction of Facebook's. The challenge is that other social media companies are more selective in what user metrics they're willing to disclose, which impedes comparability.

Social media app icons on a smartphone

Image source: Pixabay.

Twitter (NYSE:TWTR) discloses MAUs (328 million at the end of the first quarter) but not DAUs; Snap (NYSE:SNAP) discloses DAUs (166 million at the end of the first quarter) but not MAUs.

It's worth acknowledging why Facebook is so much larger than Twitter or Snapchat. The social network was always intended to be a mainstream platform that is extremely approachable with a user-friendly interface that's relatively intuitive. Twitter still refuses to abandon its arbitrary 140-character limit, which is probably the biggest hurdle to usability (who isn't sick of trying to follow a tweetstorm with branching responses?). Snapchat's interface is notoriously confusing, and first investor Jeremy Liew said this is intentional "because it breaks traditional metaphors and conventions for app design," which Liew argues is precisely why it's so popular among teens and younger users.

By appealing to the mainstream, Facebook has reached an unprecedented and unparalleled scale for a social media company. And seeing as how advertisers follow users, the financial benefits are quite obvious as well.

But wait, there's more!

Additionally, Facebook is just one of the company's expanding portfolio of social platforms, albeit the core flagship one. Messenger and WhatsApp now boast over 1 billion MAUs each, both hitting the 1 billion milestone last year. While Messenger and WhatsApp aren't contributing a whole lot financially quite yet, as Facebook is still ironing out its monetization strategy, Instagram is well on its way to becoming the company's fourth billion-user platform (Instagram hit 700 MAUs in April).

Instagram is becoming quite important, particularly as photo/video sharing services lend themselves rather well to ad monetization. Instagram's advertiser base hit 1 million in March.

Well done, Zuck Dawg. Well done.