A retargeting pixel code is a third party tag provided by a retargeting network or vendor for implementation on the advertiser pages. The tag is implemented on the web pages related to an action used for retargeting. On merchant websites it is often product pages or cart pages.
The retargeting pixel code gives instruction to the visitor’s browser to request a one single pixel image from the retargeting company servers. The retargeting network uses the request to place a cookie on the visitor’s desktop. For tracking each product seen at the product page level, a unique product ID (often a SKU) is generated with the pixel request.
Pixel implementation on the Triggit platfom:
Afterwards, thanks to the cookie, the visitor is recognised on the retargeting network and an ad with product related images can be displayed by the way of dynamic creative ads. One or several product IDs associated with the cookie are used to retrieve ad elements from the merchant product feed.
The XLM product feed used for building dynamic ads based on product IDs /SKUs:
An other example of retargeting pixel code offered by Adroll: