(CNN) – Facebook is expanding its mobile messaging network.
The social media giant has agreed to buy Whatsapp in a deal worth 19 billion dollars.
Under the terms, Facebook will pay four billion in cash and 12 billion in stock.
The agreement also provides an additional three billion in stock grants for Whatsapp’s founders and employees, if they stay employed by facebook for four years.
The C.E.O. of Whatsapp will join Facebook’s board.
Whatsapp is used by more than 450 million people.
It allows users to send text messages for free over the internet.