Apple says that its App Store brought in $10 billion in revenue in 2013. Sales hit $1 billion in December alone, when customers downloaded nearly 3 billion apps, making it the App Store's most successful month ever. In all, mobile developers have earned $15 billion from the App Store.
Apple noted that many of its most successful apps, like Candy Crush Saga, Puzzles & Dragons and Minecraft, come from developers located overseas. The company also named three mobile development firms as ones to watch: the U.S.'s Duolingo, Sweden's Simogo and the U.K.'s Frogmind.