Boston University researchers analysed 200 million ad impressions worldwide and used data from ad manager Raptive. They also examined a Google-run experiment overseen by the United Kingdom’s Competition and Markets Authority, where about 60 million desktop and mobile Chrome users were randomly assigned to three groups: cookies-enabled, cookies-disabled, or cookies replaced by Privacy Sandbox.
The study reports that removing third-party cookies reduced publisher ad revenue by about 35% overall and by about 66% in the European Union, which has stricter online privacy rules. The now-defunct Privacy Sandbox recovered only about 4% of the lost revenue.
Authors say cookies help advertisers recognise users across many sites, making advertising more efficient. They warn reduced cookie use will likely lower ad effectiveness and the revenue that supports much of the open web. Critics emphasise the privacy cost and call cookies online surveillance tools. Tech companies and publishers have tried paywalls, cross-site log-ins, and privacy-enhancing technologies in response.
Difficult words
- ad impression — one view of an online advertisementad impressions
- third-party cookie — a cookie set by a different websitethird-party cookies
- publisher ad revenue — money publishers earn from showing advertisements
- privacy-enhancing technology — tools that reduce tracking and protect privacyprivacy-enhancing technologies
- open web — free, publicly available websites and services online
- paywall — a website barrier that asks users to paypaywalls
- surveillance — close watching or monitoring of people online
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Do you think paywalls or other payment methods are a good solution for websites that lose ad revenue? Why?
- How might a drop in ad revenue affect the kinds of websites and services available on the open web?
- What trade-offs do you see between user privacy and the money that supports free websites?
Related articles
Light tool measures activity inside living brain cells
Researchers developed a bioluminescent calcium sensor called CaBLAM to record activity inside living brain cells without external light. The tool works in mice and zebrafish and enables long recordings that avoid damage from bright light.
Brothers build magnetic system to remove arsenic
Arsenic in Indian groundwater causes serious health problems. Two brothers from Bihar developed METAL, a chemical-free magnetic way to clean water and built the MARU unit; their startup Navmarg has treated over 300,000 litres and plans sensors and AI.