Google Analytics collects the following information through the default implementation:
- Number of users
- Session statistics
- Approximate geolocation
- Browser and device information
See a full list of the default events and user properties collected by Google Analytics.
Analytics also collects enhanced measurement events (when enabled) from web data streams and in-app purchases from app data streams.
Identifiers for websites
Google Analytics stores a client ID in a first-party cookie named _ga to distinguish unique users and their sessions on your website. Analytics doesn't store the client ID when analytics storage is disabled through Consent Mode.
Identifiers for mobile devices
The Google Analytics for Firebase SDK automatically generates and assigns an app-instance identifier to each instance of your app. Analytics uses the ID to identify unique installations of your app and compute user metrics. Learn more about the app-instance ID. If the client wants to send unconsented data to GA4 measurement protocol, the app_instance_id must be created per event.
The SDK has the capability to collect identifiers for mobile devices (for example, Android Advertising ID and Advertising Identifier for iOS) and uses technologies similar to cookies.
On iOS, the SDK collects the Advertising Identifier (IDFA) only if it is available. For the IDFA to be available, a developer has to link in the AdSupport.framework library and on iOS14.5+ receive user authorization from the App Tracking Transparency framework. If the Advertising Identifier is unavailable, the SDK collects the Vendor Identifier. If the Advertising Identifier becomes available after the Vendor Identifier was reported, the SDK stops collecting the Vendor Identifier.
On Android, the SDK collects the Advertising ID by default. For the Advertising ID to be available, a developer has to include the com.google.android.gms.permission.AD_ID permission in the SDK's manifest file. To collect the Advertising ID, the SDK includes the com.google.android.gms.permission.AD_ID permission in the SDK's manifest, which automatically merges into the app manifest by the Android build tools. The Advertising ID is removed when a user opts out of personalization using advertising ID in Android Settings. Any attempts to access the identifier will receive a string of zeros instead of the identifier. To learn more about the AD_ID permission declaration, see Advertising ID in the Play Console Help.