Google provides interesting statistics regarding Android OS versions installed on user devices. According to the information provided, the most popular version is Android 6.0 Marshmallow, which is installed on 32.3% of devices. At the same time, the latest version of Android 7 Nougat is available only on 13.5% of Android devices (7.0 by 12.3% and the latest version 7.1 by 1.2% of gadgets). The fifth version of Android Lollipop is second most popular and works on 29.2% of devices, 16.0 % belongs to Android4.4 KitKat (16%). The Jelly Bean version occupied a niche of 7.6% and the remaining versions of the operating system – Ice Cream Sandwich and Gingerbread – account for the remaining 1.4%. At the same time, on Apple devices, the situation with versions of the iOS operating system is fundamentally the opposite: the most current version of iOS 10 works for 87% of gadgets. Version iOS 9 owns 10 percent of the market and only 3% of devices support older iOS operating systems.