Invoice is a nonnegotiable commercial instrument issued by seller to a buyer. It identifies both trading parties as well as lists, describes, and quantifies the things sold, shows the actual date of transport and mode of transport, prices as well as discounts (if any), as well as delivery and transaction terms. An invoice is a commercial document issued seller to a buyer, relating to a sale transaction and indicating the items, quantities, and agreed prices for products the seller had provided the customer.