How can I see which invoices are outstanding?
This article explains how to see a list of invoices you've sent to your customers for which you're still waiting to receive payment. It also explains how to filter the list, to see only outstanding invoices for a particular customer.
How to see a list of outstanding customer invoices
When you click on the Invoicing module in the sidebar menu, the default screen shows you a full list of outstanding invoices - all the invoices that still require payments or part-payments.
On this screen, for each invoice, you can see the date the invoice was issued, the invoice total, the outstanding balance, and how overdue the payment is.

Filtering the list by customer
If you want to view outstanding invoices for a specific customer, click the 'By Customer' tab. Then select the customer's name from the drop-down menu.
In the 'Invoicing - By Customer' screen, outstanding invoices are shown in the first table, and fully paid invoices in the second table.

To help you better understand the invoicing module as a whole, please visit the module overview page here.