Thursday, 9:14 pm
A pair of white sneakers appears in her Instagram feed. The same pair she looked at on Monday. Nobody on the brand's team designed that ad for her. Nobody picked her either.
Rewind to Monday, 1:40 pm
She opens the brand's site, taps the sneakers, adds them to the cart and closes the tab. The Meta Pixel, a small tracking snippet on the site, records which product she touched, by its ID.
Rewind further, to a few weeks earlier
Someone on the team uploads a product feed to Meta: every item with its title, price, image, availability and ID. That upload was the whole creative effort.
Back to Thursday
Meta matches the ID from her cart to the feed, pulls the image and the current price, and builds the ad on the spot.
So what is a catalogue ad
Meta now calls it Advantage+ catalog ads; it used to be dynamic product ads. One template, a full inventory, a different ad for every viewer.
When they make sense
You sell many products, so one hand-made ad per item is unrealistic. People browse before they buy, and your site has enough traffic to retarget. Prices or stock change often, and the ad has to stay current.
When they don't
You have one hero product, and a story beats a template there. Your traffic is thin, so there is nobody to retarget and nothing to match. The product needs explaining, and an image with a price won't do it.
The detail that fails quietly
The IDs in your feed must match the IDs your Pixel sends. If they don't, Ads Manager still shows events firing and tracking looks fine, but the ads can't connect behaviour to products and retargeting underperforms.
The last step, not the first
The ad on Thursday was the last step of work finished weeks earlier.