With the launch of our App Idol competition the iPhoneAppCafe team has been buzzing with app ideas. After I proposed a series of apps that had the team shaking their heads for moral, logistical, social and legal reasons I was sent back to the drawing board to uncover what 10 characteristics make an iPhone app successful. Below you will find a list of characteristics that ensure the top performing apps stand out in a crowded marketplace of over 600,000 competitors. The most successful apps may not possess all of the characteristics mentioned in this article, but they will have at least one of them and your ability to exploit and replicate these characteristics can be the difference between the success and failure of your app as a developer.