device identification
A Device Identification (Device ID) is a unique identifier for mobile devices that is independent of the serial number.
For Apple products, the iPhone, iPod and iPad, the Device ID is called the Unique Device ID( UDID). It is a forty- digit letter-digit combination that the user can view on iTunes or with an app from the App Store. For mobile devices with the Androidoperating system, the Device ID is transferred during the first boot.