Mobile App: Unique Device ID (UDID)

UDID is a key Insider uses to detect if a user who deletes their app and installs it again comes back using the same device. 

A key is generated from each device, and assigned to it as their unique device ID. Once a user comes back to the app, Insider can detect which user is back on the app. This ID is assigned to the motherboard of the device, and the user cannot change it.

If different users use an application on the same device, their UDID would be the same in this case.

You can use UDID to segment devices, and to detect your device on the Test Lab when testing your events and attributes.