A marketer types one sentence into an assistant: "spend 50k reaching home cooks on premium recipe sites this month, keep it brand-safe." A few minutes later a campaign is live. No insertion order was emailed, no trafficker keyed a line item. Two pieces of software did the deal.
That is agentic advertising: AI agents that discover inventory, agree on terms, run the buy, and report back, with a person setting the goal and approving, not clicking through every step. It is the next move in a long pattern. You already know the earlier ones.
- 1Waterfall: partners called one at a time, in a fixed order. Slow and leaky.
- 2Header bidding: every partner bids at once in a unified auction. Faster, fairer price.
- 3Agentic: a machine, not a person, decides what to buy and executes it, talking directly to the seller’s machine.
Key idea
Two roles run the whole show. A buyer agent acts for an advertiser: it finds inventory and places the buy. A sales agent (also called a seller agent) acts for a publisher: it represents that publisher’s inventory and answers buyers. A deal is a conversation between the two.
Who is who
| Agent | Acts for | Its job |
|---|---|---|
| Buyer agent | Advertiser / brand | Translate a goal into a plan, find matching inventory, negotiate, and execute the buy. |
| Sales agent | Publisher | Expose what the publisher has to sell, quote availability and price, and accept or reject offers. |
| The human | Either side | Sets the objective and the guardrails, and approves the steps that need a person. |
Quick check
An agent represents The Weather Company’s inventory and answers questions from buyers about what is available. Is it a buyer agent or a sales agent?
What changes, and what does not
It is easy to assume agents replace everything underneath. They do not. The auction still runs. The publisher still declares its sellers in ads.txt and the SSP still publishes sellers.json. The ad server still books and serves. What changes is the layer on top: a machine now does the discovery, negotiation, and trafficking that a salesperson and a trafficker used to do by hand.
Note
This is why Tracks A to F still matter for agentic work. An agent that buys against a publisher is buying against that publisher’s real supply chain, floors, and identity setup. The plumbing is the same; the operator is new.
Quick check
Name one thing that stays the same in an agentic buy and one thing that is new.
The next two tracks are the deep dives: Track H is AdCP, the open protocol the conversation actually runs on, and Track I is the IAB Tech Lab agentic standards. First, the rest of this track gives you the shared vocabulary they both use.