Purpose of Client ID:
User Identification: The Client ID helps Google Analytics distinguish between new and returning visitors. It allows GA to track user interactions across multiple sessions, even if the user doesn’t log in or identify themselves.
Session Unification: It helps to link multiple pageviews or events to the same user within a session.
User Metrics: By default, Google Analytics uses Client ID to determine unique users in reports. However, it’s important to note that this can lead to inflated user counts if a single user accesses the website from multiple devices or browsers, as each combination will have a different Client ID.
Limitations of Client ID:
Cross-Device Tracking: Client ID cannot track users across different devices or browsers, as each device or browser will have its own unique Client ID.
Data Deletion: If a user clears their browser cookies, the Client ID is deleted, and they will be considered a new user upon their next visit.
Alternatives to Client ID:
User ID: Google Analytics offers a User ID feature for websites with login functionality. It allows for more accurate user identification across devices and sessions by assigning a persistent ID to logged-in users.
Google Signals: This feature uses aggregated data from signed-in Google users to provide cross-device measurement capabilities in some cases.
Where to find Client ID:
Browser Cookies: You can find the Client ID in your browser’s cookie storage for the website you’re visiting.
Google Analytics Reports: In some Google Analytics reports, you can see the Client ID for individual users (e.g., in the User Explorer report).
Google Tag Manager: If you’re using Google Tag Manager, you can access the Client ID through a custom JavaScript variable.
