Mobile Advertising Identifier
Most modern mobile devices (iOS 6, Android 2.3, and Windows 10 and above) provide mobile advertising identifiers. These are randomly-generated alphanumeric codes that are associated with your device that often come with options to reset the identifier and opt-out of Cross-App Advertising. These identifiers have different names depending on the operating system. For example, they are called Google Advertising ID (GAID) on Android devices whereas on iOS, they are called Identifiers for Advertisers (IDFA). They are included to provide advertisers a method to identify your devices without using a permanent device identifier, like your phone’s serial number.