Instagram just hit 400 million users. That's a lot of selfies and pictures of food.
This is more than just a milestone, though. Instagram's steady growth could spell big things for its ads and ad revenue. (Video via Instagram)
The filter-y photo service has doubled its user base since March of last year. (Video via NASA)
And 75 percent of that user base — or some 300 million users — are outside the U.S., where Instagram's potential for ad revenue is just now picking up steam.
In other words, the ad dollars might be about to catch up to the growth in a big way.
And some so-called conservative estimates say when Instagram hits maturity it could be worth $5 billion.
Re/code writes: "Instagram ads are getting more targeted and more plentiful, and Instagram's continued growth means there are (and will continue to be) more people to see those ads."