You open a news site on your phone. Before the page even finishes loading, an empty ad slot quietly held an auction, picked a winner, and the site earned a fraction of a cent. The whole thing took less time than a blink.
This lesson answers two simple questions about that moment: who was in the auction, and how did the money work? That is all. Header bidding, the thing this whole course is about, is just one link in that chain, and we will get to it. For now, take it slow. You do not need to memorize anything.
Two sides, one marketplace
Almost everyone in this business sits on one of two sides. The supply side has ad space to sell: the publisher (the site itself) and the SSPs that represent it. The demand side wants to buy that space: the advertiser and the DSPs that bid on their behalf. They meet in the middle, and an auction settles the price.
Key idea
If you remember one thing from this lesson, remember this: supply sells, demand buys. Every other term hangs off that single idea.
The players
Here are the actors you will meet over and over. Do not memorize the table, just get a feel for who is on which side.
| Actor | Side | In one line |
|---|---|---|
| Publisher | Supply | Owns the site and the ad space. Wants the highest price per ad. |
| Ad server | Supply | The publisher’s decision-maker (usually Google Ad Manager). Picks the final winner and shows the ad. |
| SSP / exchange | Supply | Represents the publisher to many buyers and runs an auction for the space. |
| DSP | Demand | Buys ad space for advertisers by bidding into exchanges. |
| DMP / CDP | Data | Supplies audience data used to decide how much an ad slot is worth. |
Quick check
An SSP and a DSP. Which one is on the supply side (the selling side)?
One ad, from request to render
Here is what actually happens in that fraction of a second, start to finish:
- 1You request the page, and an ad slot’s code runs.
- 2A quick auction asks several SSPs to bid on the slot at once. This is header bidding (the next lessons).
- 3The best bid is handed to the publisher’s ad server.
- 4The ad server compares it against its other demand and picks the overall winner.
- 5The winning ad is sent back and shown to you.
- 6The outcome is recorded, and the site earns its share.
Note
Step 2, several buyers bidding at once, is the entire reason this course exists. Everything else is detail arranged around it.
Five money words
These five come up in every later lesson. They are simpler than they sound.
| Term | What it means |
|---|---|
| Impression | One ad actually shown to one person. |
| CPM | Price per one thousand impressions. A $2.50 CPM is $2.50 for every 1,000 ads shown. |
| Fill rate | The share of ad requests that came back with a paid ad. |
| eCPM | Effective CPM: any earnings rewritten as a per-thousand price, so you can compare different deals on one scale. |
| Win rate | The share of a bidder’s bids that actually won. |
Quick check
An ad sold at a $4 CPM and was shown 5,000 times. Roughly how much did the publisher earn?
That is the whole map. In a Bidcliq Academy audit, the lines in a publisher’s ads.txt file are exactly the supply side of this picture: the list of SSPs a publisher sells through. The next lessons zoom into the auction in the middle.
Note
If the acronyms have not stuck yet, that is completely normal. You will meet each one many more times, and it becomes automatic faster than you would expect.