Apps are required to specify a
location_id when creating fulfillments. For more information, see Managing fulfillments.
You can use the Fulfillment resource to view, create, modify, or delete an order's fulfillments. This resource is most often used in apps that perform shipping-related actions, such as making tracking and delivery updates, or creating additional shipments as required for an order.
In Shopify, a fulfillment represents a shipment of one or more items in an order. When an order has been completely fulfilled, it means that all the items that are included in the order have been sent to the customer.
In most cases, a merchant will make just one shipment per order, but sometimes the availability or size of items in the order requires a merchant to make more than one shipment. Each shipment should be treated as a separate fulfillment.