A deterministic identifier is an identifier that can be definitively tied to a specific user’s device.
The most common deterministic identifiers include:
* Cookies — which, despite many actions taken by Safari and Chrome, remain an indispensible identifier in the desktop and mobile web world
* IFAs — identifiers for advertisers, which are primarily used in the in-app world. Android and iOS platforms maintain their own proprietary scheme for device identification
* PIIs — short for Personally Identifiable Information, this refers to data that can be tied to an individual, such as login info, email, phone numbers, names, social handles and others
