Apple's App Store didn't really have competition. The iPhone was pretty much an entirely new class of smartphone. The sheer volume of users compared to early sm

Apple's App Store didn't really have competition. The iPhone was pretty much an entirely new class of smartphone. The sheer volume of users compared to early smartphones meant you could sell an app for $1.99 and make loads of money, compared to Palm/WinMo apps that were more like $10+. It took off because it was a good experience (one stop shopping) and because of the popularity of the iPhone. And of course it doesn't hurt that it was the only App Store for iOS.