An online store found the page where shoppers left, and started retargeting them.

General web tracking was already in place on the store. What it did not show clearly was where shoppers left. People were dropping out somewhere between looking at a product and completing an order, and the reports could not say at which page.

The ad platforms had the same gap. There was no way to retarget someone who had looked at a product and not bought it, or someone who had left something in the cart. A retargeting audience is a list built from events, and an ad platform can only build a list from the steps the site tells it about.

The store ran on Shopify. I set up the tags in Google Tag Manager for the actions a shopper takes on the way to an order: viewing a product, adding it to the cart, and moving through the checkout to the purchase.

Each action went to three places. GA4 received it as an event, so the funnel could be read one step at a time. Meta received it through the Meta Pixel and Google Ads through the Google Ads tag, so both ad platforms could build audiences from it.

All three were fed from the same actions on the site. That is what lets the funnel report and the two ad platforms describe the same shoppers. When each platform is tagged separately, they end up holding different lists for what is meant to be the same group of people.

With the funnel actions arriving in GA4, the drop-off was visible. The client could see how far shoppers got and which page lost the most of them.

The same actions defined the retargeting audiences in Meta and Google Ads. Shoppers who looked at a product and did not buy. Shoppers who left something in the cart. Neither list could be built before.