A sales invoice is a bill that lists the details of a purchase of goods or services. This commercial document is issued by a seller to a buyer, and it usually details the payment terms of the transaction.
When looking at an invoice from the service provider's or seller's point of view, the document is a sales invoice. It allows you to tell purchasers how much money they owe you and what services or goods you sold them. From the buyer's point of view, the sales invoice is a hard copy of the receipt for anything received from the seller.
Other details that may appear on a sales invoice include a reference number to the transaction, the date of the invoice and the name and contact information of the seller.