When you turn on the order sync, the orders from your online store start syncing to Sumtracker.
When an order gets synced, the stock of SKUs in the order gets booked in Sumtracker. Below is a screenshot from the products list table that shows stock for one of the products.
Booked quantity shows the unfulfilled quantity of this SKU in open orders.
As the orders are fetched, the updated Available quantity gets synced to your online store.
When the order gets fulfilled/shipped on your store, Sumtracker automatically detects it, and
Order is marked as closed in Sumtracker
The In-stock and Booked stock levels reduce for the SKUs
For bundles, Sumtracker follows the above steps for all components of the bundle.
Order refunds, cancellations, and restock items done on your store are handled by Sumtracker automatically.