Feb. 20, 2014 -- Tech companies have a knack for making billionaires out of Internet rejects, and the refrain is all too sweet for Jan Koum, the founder of WhatsApp Inc.
He and his former co-worker at Yahoo, Brian Acton, started the mobile messaging app company that was just purchased by Facebook for $19 billion.
Here are some things you should know about Koum:
Age: 37. He will turn 38 on Monday.
Wealth: Koum may be worth $6.8 billion if he owns what Forbes believes is 45 percent of WhatsApp. With the acquisition, he is now on Facebook's board of directors.
Background: He was born and raised as an only child in a rural area outside Kiev, Ukraine. He immigrated to Mountain View, Calif., now the home of Google Inc., when he was 16, along with his mother. They emigrated as a result of anti-Semitism and political turbulence in Ukraine, Forbes reports. His family relied on food stamp assistance, Bloomberg reported.
Education: Koum dropped out of San Jose State University, where he studied math and computer science, his CrunchBase profile states.
Family: Koum's father died in 1997. His mother died of cancer in 2000.
Rejections: Both Koum and Acton, who was Yahoo's employee number 44, left the search company in 2007. They took a year off and traveled around South America, Forbes reported.
"Koum was eating into his $400,000 in savings from Yahoo, and drifting," Forbes writes.
Both were turned down after they interviewed for jobs at Facebook only about five years ago.
Acton's Twitter status on Aug. 9, 2009 states: "Facebook turned me down. It was a great opportunity to connect with some fantastic people. Looking forward to life's next adventure."
How WhatsApp started: Koum bought an iPhone in Jan. 2009, seven months after Apple's App Store launched, spurring him, with the help of others, to create an app that showed status messages next to friends in your address book, Forbes reports. It eventually became a mobile messaging system with 450 million monthly users. The 55-employee company will continue to operate independently of Facebook.
Read More: After WhatsApp, What's the Next Big Thing?