Dynamics NAV is not an accountancy system, but an Enterprise Management system. Invoices are not the general ledger entries that resume them, but the document that you ship to your customer. The ledger entries are just a result of posting the document.
Documents are used to create transactions bound to one customer (or vendor) and to one or many items or resources.
Let's see how documents work by creating a sales invoice. There are other types of documents. They will be explained in the next section.
To create an invoice such as the one in the previous screenshot, perform the following steps:
Sales & Marketing/Order Processing/Sales ...