It was a deal two years in the making, according to a source close to the situation.
Facebook CEO Mark Zuckerberg first called Whatsapp CEO Jan Koum in the spring of 2012.
A month after the call, the two went out for coffee in Los Altos. They went on a hike.
Despite Zuckerberg's wooing, the deal didn't happen.
But the two stayed in touch. There were dinners and a lot more hikes.
There were three reasons Zuckerberg was so fascinated with Whatsapp: