WhatsApp: The new billionaires behind it
Until 24 hours ago, WhatsApp founder Jan Koum and his business partner Brian Acton were relatively unknown outside Silicon Valley tech circles.
Now they are being discussed worldwide as California's latest billionaires.
The internet is alive with the news that Mr Koum, 37, and Mr Acton, 42, have sold WhatsApp to Facebook for $19bn (£11.4bn).
In fact, before founding WhatsApp, both men were actually turned down for jobs at Facebook.
This is an irony that has not been lost on internet commentators in light of the huge amount the social networking giant is laying out for WhatsApp.
So what do we know about the men behind WhatsApp?'Appreciate communication'
Ukrainian Mr Koum emigrated to the US at the age of 16 with his mother, to escape "the political and anti-Semitic environment", according to Forbes.
His childhood in the Ukraine was a seminal influence on the creation of WhatsApp, according to investor Jim Goetz. The service, with its emphasis on messaging privacy, was influenced by "growing up in a communist country with a secret police", Mr Goetz said in a blog post.
"Jan's childhood made him appreciate communication that was not bugged or taped," Mr Goetz wrote.
When he arrived in the US, Mr Koum and his mother lived on food stamps, Mr Goetz added.
Mr Koum has been shaped by his experiences, and appears to remain true to his roots, reportedly signing the Facebook deal that is set to make him a billionaire on the door of his old benefits office.No ads
Mr Koum met Mr Acton in 1997, and the two became friends while they were both working at Yahoo.
Mr Acton's background was somewhat different from Mr Koum's - his adoptive father had attempted a career in golf, and his mother ran an air-freight business, according to Wired UK.
By 2007, both men had become disillusioned with their employer, and had developed an intense antipathy to advertising, a central plank of Yahoo's business model.
"No-one wakes up excited to see more advertising, no-one goes to sleep thinking about the ads they'll see tomorrow," Mr Koum said in a 2012 blog post.
They left Yahoo to unwind and follow other opportunities, leading to Mr Koum setting up WhatsApp in 2009.
Mr Acton joined the company in November of that year after a failed job hunt, which included rejections from both Twitter and Facebook.
But the California-based software engineer took the knockback from Twitter with good humour, tweeting: "Got denied by Twitter HQ. That's ok. Would have been a long commute."
And when he also failed to get a job with Facebook, he took it graciously, tweeting: "Facebook turned me down. It was a great opportunity to connect with some fantastic people. Looking forward to life's next adventure."Silicon Valley maverick
Despite WhatsApp's emphasis on social messaging, Mr Koum has been opposed to much of what makes Silicon Valley tick.
Rather than embracing self-promotion, marketing, an advertising-funded business model and an eye for a fast buck, Mr Koum has gone in the opposite direction.
"Next person to call me an entrepreneur is getting punched in the face by my bodyguard. Seriously," he tweeted in May 2012..
"People starting companies for a quick sale are a disgrace to the valley," he said in a later tweet.
Some might say that just five years after starting, 450 million users and 50 employees later, the deal with Facebook would constitute a "quick sale".
Just don't call Mr Koum an entrepreneur.