And Facebook has been building out Messenger's abilities of late. The M voice assistant is coming to messenger soon, and it supports some mobile payments and now video calling. (Video via Newsy, Facebook)
Of course, maybe we shouldn't put too much stock in one app ranking. It only counts U.S. users, after all.
Facebook-owned WhatsApp actually has a larger monthly userbase than even Messenger, but most of its users are concentrated in Asia. (Video via CNBC)
This video includes images from Getty Images.