Google is to start serving advertisements to its users based on their browsing habits, the web giant announced on Wednesday.
The company already offers advertising related to the site being surfed — so long as that site is a Google AdSense partner or YouTube. But the beta test of what Google calls "interest-based" advertising will take a wider view of the user's surfing habits to target served ads even more accurately. The service will launch on 8 April.
"These ads will associate categories of interest — say sports, gardening, cars, pets — with your browser, based on the types of sites you visit and the pages you view," Google's vice president of product management, Susan Wojcicki, wrote on the official Google blog. "We may then use those interest categories to show you more relevant text and display ads."
The new ad-serving system works by downloading a DoubleClick cookie to the user's browser to track their path through various AdSense-using sites. DoubleClick is an ad-serving company that was acquired by Google last year.
As with any other cookie, this tracking file can be cleared by the user at any time. By visiting Google's ad-preferences page, the user can opt out of having their surfing habits tracked, or input their own preferences for the subject matter of ads they would like to see.
However, as clearing the browser's cookies would effectively remove the opt-out cookie itself, Google has also released a plug-in for browsers that provides a permanent opt-out from the service.
Google is keen to stress the transparency of its approach. "We already clearly label most of the ads provided by Google on the AdSense partner network and on YouTube," Wojcicki wrote. "You can click on the labels to get more information about how we serve ads, and the information we use to show you ads. This year we will expand the range of ad formats and publishers that display labels that provide a way to learn more and make choices about Google's ad serving."
A spokesman for Google told ZDNet UK on Wednesday morning that the company had "gone beyond the industry standard" for privacy in contextual advertising. "We were never going to be comfortable doing it unless we could offer this choice for the users," the spokesman said.
Asked whether there were any comparison to be made with Phorm, the ad-serving company that drew protests when it conducted user-monitoring trials with BT without first informing the subjects, the spokesman said Google had "been open and transparent from the start".
"The ads won't start being served across the network until 8 April," Google's spokesperson said. "Our AdSense partners are being given a month's notice. With all our AdSense partners, if they want to opt out of this sort of technology, they can. We hope that the more relevant ads are, the more advertisers would be prepared to pay for them at auction." He added that Google hopes publishers will be as positive about this technology as the advertisers themselves.
In a statement, Google also addressed the opt-out nature of the service, which means users need to make a conscious decision to stop being tracked.
"Offering an opt-in would go against the very economic model of the majority of content on the internet," Google's statement read. "Consumers prefer to see more relevant advertising, which in turn fuels many of the services on the internet. We don't want to go against a model that is giving consumers the benefits they need out of it. If certain users prefer not to receive interest-based ads, we believe that we give them clear information and tools to make that choice."
The Information Commissioner's Office also released a statement, in which it said it had spoken to Google about the service and was satisfied the company was giving users enough control over their data.
"Transparency and choice are important elements when addressing any consumer concerns about privacy and the monitoring of browser activity," the ICO's statement read. "In light of this, we are pleased that the preference manager feature allows users a high level of control over how their information is used, and that the method by which users can choose to opt out is saved permanently."