Programmatic advertising explained: RTB, DSPs, SSPs and how it all fits

Programmatic advertising is the automated buying and selling of digital ad space. Instead of emailing a publisher for a quote and signing an insertion order, software negotiates each impression — often in a real-time auction that resolves in under 100 milliseconds, while the page loads.

The players, in one table

How an RTB auction works

1. A user opens a page or app with an ad slot.
2. The SSP announces the impression to exchanges, with context (site, format, signals).
3. DSPs evaluate it against their advertisers' campaigns: is this the audience? What's it worth?
4. Bids come back, the highest wins, the creative renders — all before the page finishes loading.

The power isn't speed for its own sake. It's that every single impression is evaluated individually: you pay what each user-context combination is worth to you, instead of a flat price for a bundle of impressions someone else packaged.

Beyond the open auction

Open RTB is the entry point, but serious operations mix transaction types — non-guaranteed deals with negotiated terms, and guaranteed buys with premium publishers. We cover them in depth in PMPs, Preferred Deals and Programmatic Guaranteed. As a reference, private marketplace deals now concentrate a large share of programmatic spend because they combine automation with control over where ads run.

Why it took over

• Efficiency: one console instead of dozens of publisher negotiations.
• Data: audiences and signals decide the buy, not gut feeling about a site.
• Scale across channels: display, video, CTV, audio and even digital out-of-home are bought under the same logic.
• Measurability: one reporting layer across everything.

Where to start

You don't build this stack yourself — you get access to a DSP. For most advertisers stepping up from Google Ads and Meta, that means an enterprise DSP like DV360, accessed through a seat partner that removes the volume requirements. Start with the channels where programmatic adds the most over what you already run, and grow from there.