tl;dr
PO matching is the process of checking that an invoice's details, price, quantity, item, agree with the corresponding purchase order, and often the goods-receipt record as well, before the invoice is approved for payment.
It's a core control against overpayment and billing errors, and one of the most repetitive checks in accounts payable. Automated PO matching runs the comparison on every invoice rather than a sample, and surfaces only the genuine discrepancies for a person to resolve.
See how this works in Light's Workflows.
