The official business definition of a Purchase Order and Invoice is that a Purchase Order is a document sent from a buyer to a seller, indicating the type, quantity, and agreed-upon price for goods or services the seller will provide to the buyer. An Invoice is a document sent from a seller to a buyer, indicating the goods or services provided and the amount due for payment. The Purchase Order and Invoice are two important documents in the business transaction process, as they provide evidence of the agreement between the buyer and seller. The Purchase Order serves as a legal document that binds the seller to provide the goods or services, while the Invoice serves as a record of the transaction and provides proof of payment. Together, these documents help to ensure that the transaction is completed in a timely and accurate manner.