About the User ID feature
The User ID lets you associate engagement data from multiple devices and different sessions with unique IDs.
Each unique User ID is considered to be a unique user in Analytics, so you get a more accurate user count in your reports. When you send Analytics an ID and related data over the course of multiple sessions, you can also put individual user actions in context and start analyzing ongoing relationships.In this article:
How the User ID works: An overview
The User ID enables the association of one or more sessions (and any activity within those sessions) with a unique and persistent ID that you send to Analytics.
To implement the User ID, you must be able to generate your own unique IDs, consistently assign IDs to users, and include these IDs wherever you send data to Analytics.
For example, you could send the unique IDs generated by your own authentication system to Analytics as values for the User ID. Any engagement, like link clicks and page or screen navigation, that happen while a unique ID is assigned can be sent and connected in Analytics via the User ID.
A comparison of your data with and without the User ID
In an Analytics implementation without the User ID feature, a unique user is counted each time your content is accessed from a different device and at each new session. For example, a search on a phone one day, purchase on a laptop three days later, and request for customer service on a tablet a month after that is counted as three unique users in a standard Analytics implementation - even if all these actions happen with an account sign-in. While you can collect data about each of these interactions and devices, you can’t determine if any relationships exist. You only see independent data points.
When you implement the User ID, you can identify related actions and devices and connect these seemingly independent data points. That same search on a phone, purchase on a laptop, and re-engagement on a tablet that previously looked like three unrelated actions on unrelated devices can now be understood as three related actions on related devices. This gives context to your analysis and so you can get a holistic view of your users and their behaviors.
Session unification is a User ID setting that allows hits collected before the User ID is assigned to be associated with the ID. This can help you analyze the user behaviors that lead up to the action that triggered the User ID assignment. You can turn session unification ON and OFF, and the setting changes what data is associated with the User ID. Learn more about session unification.
To set up the User ID, you must first enable the feature in your Analytics account and then modify your tracking code. Follow the User ID set up overview for guidance on enabling the feature in your account.
Refer to our Developer Guides for information on how to add the User ID to your tracking code.