A purchase order number is a unique identifier assigned to a purchase order, which is an official confirmation of a buyers intent to purchase from a vendor, covering the details of the transaction. The PO number helps both vendors and buyers track and reference the orders theyve sent or received, and it is crucial in facilitating a three-way match system involving the purchase order, the receiving report, and the vendors invoice. The purchase order number is important for managing and tracking purchases, as well as an asset in record-keeping for AP and accounting teams. It allows companies on both sides of a transaction to maintain and easily reference their purchase orders, helping both vendors and buyers hold each other accountable for order details and giving auditors and accountants easy access to the documents for tax purposes. The purchase order number can be generated manually or through an application like Excel, and it can be a mix of numbers, letters, and dashes arranged in a way to suit the business and its processes.