How services recognise an app installation

A service can link activity without knowing a person's name. The same identifier on two records can connect them to one visit, installation or account.

Identifier	What it can connect
Session ID	Activity during one visit.
Installation ID	Use of an installed app over time.
Account ID	Activity belonging to an account, possibly across devices.
Advertising ID	Activity associated with the platform's advertising code.
Publisher ID	Activity associated with a publisher's own code.
Push token	Delivery of notifications to an installation.

Removing an advertising ID does not remove account IDs or the identifiers needed for notifications. A random-looking value can still make repeated activity recognisable.

The app pages describe which optional tracking the patches reduce. Services that remain available can still use identifiers. See Snowplow's identifier guide for background.