Save some additional order details, such as payment results, and add notes to the order for customers to view. Some payment gateways also add notes for debugging.
In the Status & Comments page the store owner can change the status of an order, type a new comment to the customer to read when logged into their store account, and by checking the "Notify Customer" and "Append Comments" checkboxes the customer is notified via email and a new comment is added for tracking.
NotifyCustomer - If the customer is notified, they will receive an email in the format of the order confirmation email.
The notes feature can be a very powerful tool for communicating with customers. Need to add a tracking number for shipping? Some stock is delayed? Add a customer note and they will be automatically notified.