Almost every day, internet users are asked the same question: Do you accept cookies?
For many people, clicking “reject” has become automatic.
Concerns about privacy and online tracking have made users increasingly uncomfortable with the idea that websites and advertisers are following their behavior across the internet.
But new research from Boston University suggests that refusing cookies may have an unintended cost.
According to the researchers, internet cookies still play a major role in supporting the free websites and online services many people use every day.
The study examined what happens when websites can no longer use third-party cookies, which are small pieces of code placed by advertisers or outside companies rather than the website itself.
These cookies help advertisers recognize users as they move across different websites, allowing ads to be more targeted and effective.
The researchers analyzed around 200 million online ad impressions from around the world. They found that removing cookies reduced advertising revenue for website publishers by more than one-third overall. In the European Union, where stricter privacy laws already limit tracking, revenue losses reached about 66%.
The findings were published in the journal Proceedings of the National Academy of Sciences.
Professor Garrett Johnson explained that cookies have long been central to the online advertising system. Because advertisers can better identify who may be interested in certain products, they can spend their advertising money more efficiently. That money helps support news websites, blogs, videos, apps, and many other free online services.
Without cookies, advertisers may struggle to target users effectively, meaning publishers and content creators earn less money.
At the same time, many internet users dislike cookies because they feel they are being watched online. Critics often describe cookies as surveillance tools that collect large amounts of personal browsing information.
As public concern about privacy grows, technology companies have tried to create alternatives that protect user privacy while still allowing digital advertising to work.
One of the best-known efforts was Google’s Privacy Sandbox project. Instead of tracking detailed browsing history, the system attempted to group users by general interests. However, the Boston University researchers found that Privacy Sandbox recovered only about 4% of the advertising revenue lost when cookies were removed.
The system also created technical problems, including slower ad loading times and limited adoption across the industry.
The study used data from advertising company Raptive and included a large experiment involving about 60 million Chrome users. Participants were randomly assigned to different browsing conditions: normal cookies, no cookies, or Privacy Sandbox replacements.
The researchers say the results help explain why Google eventually abandoned its plan to replace traditional cookies entirely.
The findings also arrive as governments around the world debate even stricter online privacy rules. The researchers argue that policymakers should carefully consider the economic effects such rules may have on the open web.
Johnson says the decision ultimately comes down to personal preference. While many people may still prefer stronger privacy protections, he personally leans toward accepting cookies because he believes they help support the websites and online creators he values.
