It’s unusual when a company as young as Facebook drops $19 billion on an acquisition, especially when its on a company some folks hadn’t even heard of. But the messaging juggernaut called WhatsApp is huge (in terms of users and messages) and dangerous (in terms of the threat they posed to Facebook) and totally mobile (which is where Facebook needs to be). Here’s Buzzfeed on why Facebook had to have WhatsApp.

+ WSJ: What is WhatsApp? One highly addicted user explains.

+ Kara Swisher: “We have now established a price floor for what it costs not to have a mobile operating system in a world in which having a mobile operating system counts for an awful lot these days.”

+ Aside from the race towards mobile and the acquisition of a ton of active users, I think there are a couple interesting aspects to this deal. First, WhatsApp is really about sending messages to individuals or small groups. These messages are usually more private than Facebook posts. Private is the new public. Second, WhatsApp prides itself on not collecting data about its users and then selling that information to highest-bidding advertiser. The app has no ads at all. Facebook has derived much of its value from the data collection and advertising model. In other words, the value of your personal data helped pay for a company that doesn’t collect any of it.