Procure-to-Pay (P2P) is the end-to-end business process spanning purchase requisition, purchase order, goods receipt, invoice matching, and supplier payment. P2P is the operational transaction backbone that Contract Performance Management sits above.
The P2P chain
Requisition -> approval -> PO -> goods receipt -> invoice -> matching -> payment. Each step is typically supported by ERP or specialized procurement software. The transactional data flows through and into the ERP as the system of record.