* Facebook is buying mobile messaging service WhatsApp for $19 billion in cash and stock.
* Facebook, world's biggest social networking company, is paying $12 billion in Facebook stock and $4 billion in cash for WhatsApp.
* Facebook's WhatsApp acquisition is Mark Zuckerberg-led company's biggest deal.
* Facebook-WhatsApp deal bigger than any that Google Inc, Microsoft Corp or Apple Inc have ever done.
* Facebook's WhatsApp deal translates to roughly nine per cent of Facebook's market value. In comparison, Google's biggest deal, Motorola Mobility, stood at $12.5 billion, while Microsoft's largest was Skype at $8.5 billion. Apple, meanwhile, has never done a deal above $1 billion.
* Facebook to keep WhatsApp as a separate service, just as it did with Instagram.
* WhatsApp is founded by Jan Koum, a Ukrainian immigrant who dropped out of college, and a Stanford alumnus, Brian Acton.
* WhatsApp is a Silicon Valley startup fairy tale, rocketing to 450 million users in five years and adding another million daily.
* While WhatsApp has more than 450 million monthly active users, Twitter, in comparison, had 241 million users at the end of 2013.
* Post deal with Facebook, WhatsApp founders and employees 55 in all will be granted restricted stock worth $3 billion that will vest over four years after the deal closes.
* With WhatsApp acquisition, the 10-year-old Facebook looks to attract its next billion users while keeping its existing 1.23 billion members, including teenagers, interested.
* Facebook-WhatsApp deal is expected to close later this year.