Android is an open-source operating system developed by Android Inc. and currently owned by Google. It was first released in 2008 and has since become one of the most popular mobile operating systems in the world, with over half a million new Android devices activated daily. While Android and iOS are similar in functionality, a key difference is their respective app markets - the Android Market currently has over 200,000 apps compared to 550,000 for the Apple App Store, and Android also has a higher percentage of free apps available.