A device can be a mobile phone, a tablet, a desktop computer, a digital screen, or any other apparatus that captures user interactions (i.e. the user launches an app, the user visits a website, etc., ) and translates them into requests to the backend servers.
Since a device sends requests on behalf of the user, the terms device and anonymous user are used interchangeably. This is particularly important in use cases where user registration is not required, since it allows advertisers to deliver custom experiences by targeting device demographics such as manufacturer, model, OS version, etc.
By getting user permission to access GPS data, additional targeting capabilities are made available to advertisers. For more information, refer to Geofence trigger.