A proforma invoice is a preliminary or provisional invoice sent by a seller to the buyer before the actual delivery of goods or services. It provides detailed information about the goods or services to be supplied, including the quantity, description, price, and any terms or conditions of the sale. Unlike a regular invoice, a proforma invoice is not a request for payment but serves as a quotation or estimate that allows the buyer to review the proposed transaction and make payment arrangements before the actual delivery or completion of the order.

By sending a proforma invoice, the seller communicates the terms and conditions of the sale to the buyer, including the payment requirements and expectations. It enables the buyer to assess the costs, terms, and other details of the transaction before making a commitment.