A quick reference for terms that get used once, then assumed. Come back here any time a word from an earlier chapter goes fuzzy.
Pixel / DatasetThe tracking code on your site that reports back to Meta. Same thing — Meta's interface increasingly labels it “Dataset.”
Conversions APIA server-side backup to the pixel, sending the same data directly from Meta's systems rather than relying on the browser alone.
ABOAd Set Budget Optimisation — the manual option. Each ad set gets its own fixed daily budget.
Advantage+ Campaign BudgetFormerly CBO. Meta's automatic option — it shifts budget between ad sets on its own.
CTRClick-Through Rate — the percentage of people who saw your ad and clicked it.
CPCCost Per Click — what each click costs you.
CTACall to Action — the instruction telling someone what to do next.
Learning phaseThe roughly 50-event window Meta needs after launch, or after a major edit, before delivery stabilises.
Custom AudienceA group built from a specific action someone took on your site — a purchase, an add to cart, a page view.
Warm audienceA Custom Audience that's grown large enough to target directly, rather than only exclude.
Cold audiencePeople with no prior contact with you. Everyone in your first campaign.
Outbound CTRThe percentage of people who saw your ad and clicked a link taking them off Meta and onto your site. Plain CTR also counts clicks on the image, the profile name and “see more” — outbound is the honest number.
Click-to-View RatioOf the people who clicked your link, the percentage whose browser actually finished loading your page. A low figure is a speed problem, not an ad problem.
EventA single tracked action on your site — a page view, an add to cart, a purchase. When Meta talks about needing fifty events, it means fifty of these.
ImpressionOne showing of your ad. Ten people seeing it twice each is twenty impressions.
ReachThe number of separate people who saw it. In that example, ten.
FrequencyImpressions divided by reach — how many times the average person has now seen the same ad. Above roughly three on a cold audience, results usually start sliding.
CPMCost per thousand impressions. What Meta charges you for showing the ad, before anyone does anything.
CPACost Per Acquisition — what one sale costs you in ad spend. The number that decides whether a campaign is profitable (Chapter 8).
Contribution per saleWhat's left from one sale after product cost, payment fees, shipping and refunds. Not the same as the selling price, and the figure your CPA has to beat.
ROASReturn On Ad Spend. Revenue divided by ad spend — a ROAS of 3 means £3 back for every £1 out.
CreativeThe industry word for the image, video or reel itself, separate from the caption.
PlacementWhere the ad appears — Facebook Feed, Instagram Feed, Reels, Stories, and others.
Attribution windowHow far back Meta looks when deciding whether a sale came from your ad. The usual default is seven days after a click, one day after a view.
Special Ad CategoryA declaration Meta requires for ads about credit, employment, housing, or social and political issues (Chapter 5).
Audience overlapThe same people sitting in more than one of your ad sets, so your own ad sets compete against each other (Chapter 13).