When Apple released the original iPhone in 2007, the device came with a handful of pre-installed applications. Safari, Weather and Stocks were among the few tools that early iPhone users had at their disposal. From today's point of view, the original iPhone was pretty limited in its functionality, but back in 2007 the device's innovative touch interface along with its design was enough to put consumers in awe.
The initial hype would probably have died off pretty quickly had Steve Jobs not changed his mind about opening up the iPhone to external software developers. Notoriously reluctant about ceding control over his products, Jobs had originally rejected the idea of external developers 'messing' with the iPhone. However, something must have changed his mind and in Spring 2008, Apple announced the first software development kit for iOS. On July 10, 2008, the App Store was officially launched by Apple and the iPhone subsequently learned hundreds of new feats.
The App Store became a great success and soon the idea of an iPhone without the App Store became unthinkable. By May 2013, Apple users had downloaded 50 billion apps from a selection of almost a million games, tools and gimmicks.
You will find more statistics at Statista