A PO (purchase order) and PR (purchase requisition) are two important but distinct steps in purchasing products for a business. The purchase requisition is an internal document used to manage the purchasing process, while the purchase order is an external document sent to a vendor. When an employee sees the need to buy goods or services (say, office supplies or a focus group service), they first fill out and submit a purchase requisition. This is essentially a request for permission to make the purchase. If this request is approved, then a purchase order is created and submitted to a vendor.