What is Retargeting?

Retargeting works by tagging: when a shopper views a product page, a pixel or script places them into an audience segment on an ad platform. Later, as they browse other sites or scroll social feeds, the platform recognizes them and serves ads for the product they viewed — often with dynamic creative pulled straight from your catalog. Because it targets people who already showed intent, retargeting typically posts the highest return on ad spend of any campaign type.

Mechanically, retargeting is cross-site tracking in its purest commercial form. It requires recognizing the same person on your site and then again on unrelated properties, historically via third-party cookies and increasingly via logged-in platform identity (Meta and Google recognize their own users everywhere) plus server-side event feeds like the Conversions API.

That mechanism drives the legal treatment. In the EU, the trackers that build retargeting audiences require prior opt-in consent — a visitor who declines cookies must not enter your audiences. In California, sending visitor data to an ad platform for retargeting is 'sharing' for cross-context behavioral advertising under the CPRA, which consumers can refuse via a Do Not Sell or Share link or the GPC signal; the Sephora enforcement action established that ordinary analytics-and-ads arrangements count.

Consent-aware retargeting is entirely workable: audiences shrink to consenting users, and modeled conversions fill measurement gaps. What is not workable is the default configuration — pixels firing on page load for everyone — which turns your best-performing channel into your largest compliance liability.