deviceID

Deviceid is a general term for a unique identifier assigned to a device to enable recognition across apps and services. It can be hardware-based, tied to physical components, or software-based, generated and managed by the operating system or applications. The main purpose is to allow a system to identify a device over time for tasks such as authentication, licensing, analytics, personalization, and fraud prevention.

Hardware-based identifiers include IMEI, MEID, ESN on mobile devices, MAC addresses, and device serial numbers. These values are typically persistent and tightly bound to the device hardware, making them harder to change.

Software-based identifiers are exposed or created by platforms, such as Android ID, iOS identifierForVendor (IDFV), advertising identifiers (IDFA on iOS and the Advertising ID on Android), and Windows Advertising ID. Some of these can be reset by the user or after events like factory resets, while others remain more stable.

Common uses include binding licenses to a device, tracking activity for analytics and personalization, mitigating fraud, and enabling push notifications or data synchronization across services. In web contexts, device identifiers may be complemented or replaced by cookies, local storage, or device fingerprinting, which attempts to identify a device based on a collection of attributes.

Privacy and policy considerations are important. Many jurisdictions require user consent for certain identifier usages, and platforms offer controls to reset, limit, or opt out of specific tracking. Best practices emphasize using the least invasive identifier, minimizing cross-app tracking, informing users, and securing identifiers against leakage.