Insertion order (IO)
An insertion order is the contractual document confirming a media buy directly with a publisher or vendor: placements, dates, volumes, rates and terms. IOs govern reserved and sponsorship inventory, and their operational workflow is a core part of traditional buying operations.
In practice
In digitally-led operations, IOs persist for direct premium buys, partnerships and offline media, alongside auction-based buying that needs no such paperwork.
IO-heavy workflows - RFPs, orders, delivery confirmation, reconciliation - are a key reason full-service agencies need broader operational systems than digital-first teams.