How Does Programmatic Advertising Work? Step by Step

How does programmatic advertising work, in short?

Programmatic advertising works in two layers. The first is the setup you do in advance inside a demand-side platform (DSP): budget, audience, inventory, bids, creatives and tracking. The second is the automated trade that happens every time someone opens a page, app or video, when the DSP decides in a fraction of a second whether to buy that impression and at what price.

If the terms are new to you, start with our plain-English guide on what programmatic advertising is. This post follows one impression through the system, then looks at the work that surrounds it.

What happens in the split second before an ad loads?

Take a typical open auction impression on a news site or app.

1. A person opens a page or app. Say a reader in Indore opens a cricket score page on their phone at 9 pm.
2. The publisher's ad code asks for an ad. The page has an ad slot, for example a 300x250 banner. Its code asks the publisher's ad server and its selling partners for demand.
3. The supply-side platform builds a bid request. The SSP or exchange describes the opportunity: the site or app, the slot size and position, the device and operating system, an approximate location, the time, and any identifiers the person has agreed to share.
4. The bid request goes out to many DSPs at once. It usually travels in OpenRTB, the common format maintained by the IAB Tech Lab, so every buyer can read it.
5. Each DSP checks its live campaigns. It filters out line items that do not match: wrong city, wrong audience, frequency cap already reached, budget spent, site on an exclusion list, no creative in the right size.
6. The DSP prices the impression. For each line item that still qualifies, it works out what the impression is worth to that advertiser, based on the bid strategy and goal, and sends back a bid along with the ad's details.
7. The exchange runs the auction. It compares bids with the publisher's floor price and with each other, and picks a winner. Most exchanges now run first-price auctions, so the winner usually pays what it bid.
8. The winning ad is served and measured. The creative loads in the slot, and tracking records the impression, whether it was viewable, and any click or later conversion.

All of this happens while the page is still loading. Exchanges give buyers a strict deadline, measured in milliseconds, and bids that arrive late are left out of the auction.

What information does a bid request carry?

The bid request is all a DSP knows about an impression before it bids. The table shows a simplified version, with illustrative values.

CPM means cost per mille, the price for 1,000 impressions. Bids are expressed this way even though each auction is for a single impression.

A bid request does not tell the buyer who the person is by name. Audiences are matched through identifiers and segments, which is why consent, data rules and the decline of third-party cookies matter so much to how well targeting works.

How does a DSP decide how much to bid?

It depends on the bid strategy you choose. There are two broad approaches.

• Fixed bid. You tell the DSP to bid up to, say, ₹120 CPM on every impression that matches. It is simple and predictable, and common on deals, but it values a strong impression and a weak one the same way.
• Automated bidding. The DSP predicts, impression by impression, how likely each one is to deliver your goal (a view, a click, a conversion) and how its price compares with the market, then bids more, less or not at all. In DV360 you can set this at the insertion order or line item level.

Automated bidding needs data to learn, so the first weeks of a campaign are usually less efficient than the weeks after. We explain how these models work, and where they fall short, in how AI optimises programmatic advertising. For the auction itself, including first-price rules and floors, see what real-time bidding is.

How do private deals and Programmatic Guaranteed change the flow?

Deals use the same pipes with one difference: the bid request carries a Deal ID that links it to terms you agreed with the publisher in advance.

• In a private marketplace (PMP), the publisher invites selected buyers. Steps 3 to 8 still happen, but only invited buyers compete, above an agreed floor.
• In a preferred deal, you get first look at the inventory at a fixed price. Your DSP can take or pass on each impression.
• In Programmatic Guaranteed (PG), you have booked a fixed number of impressions at a fixed CPM. The publisher reserves them for you and your DSP is expected to take them. If your line item's targeting is narrower than the deal, delivery falls short, which is the most common PG problem.

We buy premium OTT inventory such as JioHotstar, ZEE5 and SonyLIV through PG deals in DV360. You can see the range of deal inventory on our premium publishers page, and our guide to Programmatic Guaranteed vs PMP vs open auction explains when each type fits.

What does the advertiser set up before any of this happens?

The split-second trade only works as well as the rules behind it. Before launch, someone has to do seven things.

1. Write the plan. Goal, budget, audience, markets, channels, buying types and KPIs. Our guide to building a programmatic media plan covers this.
2. Build the campaign structure in the DSP. In DV360 it runs partner, advertiser, campaign, insertion order and line item. The insertion order holds the main budget and flight dates, and the line items under it hold the bids, targeting and inventory.
3. Choose inventory. Open auction exchanges, PMPs and PG deals, plus site and app inclusion or exclusion lists.
4. Add audiences and targeting. First-party lists, Google audiences, contextual categories, location, language, device and time of day.
5. Upload and approve creatives. Each size and format needs its own creative, and some publishers review ads before they run.
6. Set up tracking. Conversion tags such as Floodlight activities on your site, links to your analytics, and third-party verification if you use it.
7. Set pacing and frequency. Even or front-loaded pacing, and a cap on how many times one person sees the ad in a day or week.

For the DV360 screens themselves, our walkthrough on creating a campaign in DV360 goes through them one by one.

What happens after the ad is served?

Each served ad starts a measurement trail. The DSP records the impression and its cost. Viewability measurement records whether the ad was actually on screen. Clicks and site visits are tracked through tags, and conversions are matched back to the impressions or clicks that came before them, within the lookback window you set.

That data feeds two loops. In the automated loop, bidding models update their predictions as results come in. In the human loop, a trader reads the reports, moves budget between line items, adds exclusions, refreshes tired creatives and adjusts frequency caps. Both matter, and neither works well without the other. Our checklist for optimising DV360 campaigns lists what to review daily and weekly.

A worked example: one impression, start to finish

This example uses made-up numbers to show how the money moves.

A two-wheeler brand is running a DV360 campaign aimed at adults aged 21 to 35 in Madhya Pradesh, with automated bidding capped at an average of ₹150 CPM and a frequency cap of three ads per person per week.

• A 24-year-old in Indore opens a cricket site on his phone. The SSP sends out a bid request with a floor of ₹60 CPM.
• Three DSPs respond. Two bid ₹90 and ₹110 CPM. The two-wheeler brand's line item predicts this reader is a good match and bids ₹135 CPM.
• In a first-price auction, the brand wins and pays ₹135 CPM. For this one impression that is ₹0.135, or 13.5 paise.
• He has now seen the ad once this week, so the brand can show it to him at most twice more before the cap resets.
• Across a ₹6 lakh flight at an average ₹120 CPM, the same process repeats about 50 lakh times (₹6,00,000 ÷ ₹120 × 1,000).

Where does the process usually go wrong?

• Deals that do not deliver. A PG or PMP line item with targeting narrower than the deal, the wrong video length or a missing creative size will quietly block delivery. Check every new deal daily for its first week.
• Spoofed or low-quality supply. Some sellers misrepresent the site they are selling. Publishers declare their authorised sellers in an ads.txt or app-ads.txt file, and SSPs list theirs in a sellers.json file, both IAB Tech Lab standards. Buying only through authorised sellers removes much of this risk.
• Weak signals. Third-party cookies and mobile ad IDs are less available than they used to be, so audience lists match fewer people. Consented first-party data and contextual targeting fill the gap.
• Tracking gaps. If conversion tags are missing or firing twice, automated bidding optimises towards the wrong signal and nobody notices until the results look odd.

Next step

If you would rather not build and run all of this in-house, our DV360 Managed Service covers planning, setup, deals, optimisation and reporting. If you want to see the numbers first, start with a free media plan.