Installed apps can create metafield definitions for information they need, such as personalization details, fulfillment references, or data synchronized from another service.
What your staff can do
The app chooses whether its definition is editable, read-only, or hidden in Store Admin. When a field is read-only, you can view its value but only the app can change it. Hidden app data does not appear in your custom-data editors.
What other apps can use
An app can keep its metafield data private or share it with other authorized apps. Sharing does not make the value public on your storefront; storefront access is controlled separately.
Keeping integrations in sync
Connected integrations can subscribe to metafield changes when they have access to that data. A private app field is hidden from other apps only. Your staff still see it in Store Admin, and your store's own webhook subscriptions still receive its changes, unless the app hides the field from Store Admin.