The Deal Behind Every Ad
If you have never bought or sold an ad, this chapter is for you. It defines every word the trade uses, because the rest of the book uses them freely. If you’ve run campaigns or monetized a site before, skip ahead — nothing here will surprise you.
Two strangers with matching problems
A publisher owns a place readers visit — a travel blog, a recipe site, a local news page. The readers cost money to serve and the writing costs money to produce, but the readers don’t pay. What the publisher has is attention.
An advertiser has the opposite problem: a pilates studio, an online shop, an airline — something to offer and nobody looking. What the advertiser lacks is attention.
Advertising is the trade between them. The publisher sets aside rectangles on the page — slots — and rents them out. The advertiser fills them with a message. Everything else in this book is machinery for making that trade fair, fast, and worth everyone’s while.
The units of the trade
One person seeing one ad, once, is an impression. It is the atom of the business: it’s what gets counted, priced, and paid for.
A single impression is worth a fraction of a cent, so prices are quoted per thousand: CPM, cost per mille. “A $5 CPM” means five dollars for a thousand views. When this book says an advertiser “bids $5,” that is the number being bid.
The ad itself — the images, the words, the layout, the thing a reader actually sees — is called a creative. It’s an odd noun, but it is the industry word and the book uses it constantly: one advertiser might run several creatives, to see which one readers like.
A campaign is the advertiser’s standing order: these creatives, this daily budget, this CPM bid, aimed at this kind of content. Campaigns are what compete for slots.
Why an auction
At any moment, many campaigns want the same slot. Someone has to decide who gets it and at what price, millions of times a day, with no humans negotiating. The answer nearly everywhere — including here — is an auction: every eligible campaign names its price, and the machinery picks a winner.
Auctions come in two flavors, and the difference matters enough that this book has a chapter about it. In a first-price auction the winner pays what they bid — which punishes honesty, because bidding your true maximum means overpaying whenever the competition is weak. So first-price bidders hire software to guess the minimum winning bid, a practice called bid shading. In a second-price auction the winner pays what was needed to win — just above the runner-up’s bid. Overbidding no longer costs you anything, so the safe strategy is simply to bid what the impression is worth to you. The price the winner actually pays, in either flavor, is called the clearing price.
The publisher, for their part, can set a floor — a minimum price below which the slot simply doesn’t sell. Floors protect against thin competition: with only one bidder, “just above the runner-up” would otherwise mean nearly free. The catch is that a floor set too high scares off every bidder and the slot earns nothing at all — an unsold slot is called unfilled, and the share of slots that do serve an ad is the publisher’s fill rate. Choosing a floor is a genuine dilemma, and this book devotes a chapter to measuring the answer instead of guessing it.
Where the money goes
The advertiser’s daily budget caps what a campaign may spend per day — and spending it well means making it last the whole day, not just the morning (that problem is called pacing). Each impression’s clearing price is subtracted from the budget, the platform keeps a small percentage as its margin, and the rest is the publisher’s earnings. The daily bookkeeping that turns a stream of impressions into money owed and money earned is settlement.
That’s the entire vocabulary: two parties, a slot, an impression, a price per thousand, an auction, a floor, a budget, and the split. The rest of this book is how Promovolve runs this old trade differently — starting with the story of one page, one reader, and one ad.