In South Korea, there's no escaping KakaoTalk. The country has a smartphone penetration rate of 73 percent, according to research firm EMarketer, and of those people, 93 percent use the mobile messaging app Kakao, says Nielsen.
Kakao expects its app will generate about $200 million in revenue this year, according to the company's forecasts. That's compared with $42 million last year, with a profit of $6.5 million.
