Our best offer:

Lock in a year of Digiday+ for 35% less. Ends May 29.

SUBSCRIBE

WTF is piggybacking?

This article is a WTF explainer, in which we break down media and marketing’s most confusing terms. More from the series →

Piggyback rides can be fun for children. For website operators, not so much. 

Piggybacking — also known as cookie-syncing — is how an ad tech firm can drop a third-party cookie on a website’s visitors without being granted access by the website via another ad tech firm that the website has granted access, as covered in the explainer skit above. 

An issue with this third-party tracking daisy-chain is that it makes it difficult for website operators to rein in outside companies’ abilities to collect information about their audiences, which risks putting the operators in privacy regulators’ crosshairs.

More in Marketing

Retail media strategies

TikTok Shop says sales from U.S. small businesses climbed 66% in 2025

U.S. small businesses on TikTok Shop increased sales by 66% in 2025 compared to the year before.

Walmart warns it may have to raise prices due to fuel costs

The possibility comes as higher fuel prices are already putting pressure on household budgets.

OpenAI gives ChatGPT ads a visual upgrade

OpenAI is building on its single ad format to include some new iterations that give advertisers more optionality over their appearances.