Facebook has made one of the most expensive tech acquisitions in recent history this week buy buying WhatsApp for $19 billion. The question is, what did Facebook just buy? WhatsApp is one of the fastest growing apps in history: it’s got about 450 million users and the company says it’s adding one million new users a day. Jalak Jobanputra, a venture capitalist at Future Perfect Ventures, said most of that growth is happening outside the U.S.:  

“So the WhatsApp customers, especially in the emerging markets in places like India are very young.” 

But Jobanputra says, in emerging markets, WhatsApp also appeals to people of all ages because it’s basically free texting.