It’s official: Facebook now has two billion monthly users. In other words, more than 25 percent of the entire world’s population uses Facebook every month.
Facebook and CEO Mark Zuckerberg are no doubt already thinking about hitting three billion users, but the path to that number promises to be much, much harder.
For starters, much of the world still doesn't have the internet, which is why Facebook is building things like internet-beaming drones and laying fiber cable in Africa. That’s going to take some time.
The second big obstacle is China, where Facebook is banned from reaching the county’s more than 700 million internet users. If Facebook ever gets into China, three billion could be here much quicker than expected.
This article originally appeared on Recode.net.