A device’s Unique Device Identifier, or UDID, is a 40-character hexadecimal number that is specific to each Apple device, including iPhones. This identifier allows developers and other authorized entities to distinguish between individual devices. An example of a UDID is: “e4d909c0fb0d0f910d08682fb068ff00a0a2bcd”. It was historically used for device tracking and identification purposes.
Knowledge of a device’s unique identifier is important for mobile app development and testing. Developers may need this number to register devices for beta testing, to track app usage across specific devices, or to tailor application performance and features. In the past, the UDID was heavily relied upon for targeted advertising, but due to privacy concerns, Apple deprecated its use in favor of more privacy-preserving alternatives.
