Final answer:
The fundamental document in the billing process is a sales invoice, which itemizes the sale and formally requests payment from the buyer.
Step-by-step explanation:
The basic document created in the billing process is the sales invoice. This document is a critical part of business transactions as it provides a detailed record of the sale, including descriptions, quantities, prices, terms of sale, and more. It is issued by the seller to the buyer as a formal request for payment.
A sales order is a document created after a customer places an order but before the billing process. A bill of lading is used for shipping and outlines the details of goods in transit. Meanwhile, a packing list accompanies a shipment of goods and lists the contents of the package.