You can use webhook subscriptions to receive notifications about particular events in a shop. After you've subscribed to a webhook, you can let your app execute code immediately after specific events occur in shops that have your app installed, instead of having to make API calls periodically to check their status.
For example, you can rely on webhooks to trigger an action in your app when a customer creates a cart, or when a merchant creates a new product in their Shopify admin. By using webhooks subscriptions you can make fewer API calls overall, which makes sure that your apps are more efficient and update quickly.
For more information on how webhooks work, refer to Webhooks.
If you create a webhook subscription through the Shopify admin, then the webhook won't be returned in API calls. These webhook subscriptions are associated solely to the shop, so the API can't access them.
Webhook subscriptions are scoped only to the app that they're registered to. This means that when a webhook subscription is registered to an app, other apps can't view, modify, or delete it.
To learn how to verify webhooks, refer to Manage webhooks with the Admin API.