The App Opened event will fire every time a user opens your app from a closed state. This means the user does not have the app currently opened upon clicking directly on the app, receiving a notification, or entering via a deeplink.

The Event Properties unique to the App Opened event include:

"event_properties": {
        "event_id": "4ge4db71-42e9-41e8-8bb7-bd098e9e99d9",
        "app_open_source":  "direct",
        "notification_id": null,
        "notification_type": null,
        "segment_id": null,
    }

event_id String : The unique identifier of the session associated with the event. This event will also exist on the Event object level as well.

app_open_source String : This will indicate if the source of an install was direct or via a specific deeplink

Note: To view all the various sources, reference the Event Sources page

notification_id String : The unique identifier of a push notification campaign associated with the App Open. This field will only populate if the app_open_source includes a value of "push"

notification_type String : Distinguishes the various types of push notification campaigns sent. These can occur from the dashboard or even an automated push campaign

segment_id String : The unique identifier of an automated push campaign. These campaigns would distinguish between welcome campaigns, abandoned cart messages, and any other automations enabled

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Note
All events include Session Properties, Device Properties, App Properties, and Shopify Properties that are present on the Event Object. For more information, refer to the Common Event Object & Metadata document.
Event Properties, however, are unique to every event and are outlined in this page.