Google Adds a Safeguard on Privacy for Searchers

SAN FRANCISCO, March 14 — Web search companies collect records of the searches that people conduct, a fact that has long generated fears among privacy advocates and some Internet users that valuable personal data could be misused.

Now Google is taking a step to ease those concerns. The company keeps logs of all searches, along with digital identifiers linking them to specific computers and Internet browsers. It said on Wednesday that it would start to make those logs anonymous after 18 to 24 months, making it much harder to connect search records to a person. Under current practices, the company keeps the logs intact indefinitely.

“We have decided to make this change with feedback from privacy advocates, regulators worldwide and, of course, from our users,” said Nicole Wong, Google’s deputy general counsel.

But it is unclear whether the change will have its intended effect. Privacy advocates reacted with a mix of praise and dismay to it.

“This is really the first time we have seen them make a decision to try and work out the conflict between wanting to be pro-privacy and collecting all the world’s information,” said Ari Schwartz, deputy director of the Center for Democracy and Technology, an advocacy group. “They are not going to keep a profile on you indefinitely.”

Others were less enthusiastic.

“I think it is an absolute disaster for online privacy,” said Marc Rotenberg, executive director of the Electronic Privacy Information Center. Mr. Rotenberg said his organization has been trying to combat efforts by law enforcement officials to require online services to retain search records for long periods of time.

He said that 18 to 24 months was too long, and added that because of Google’s dominant position, it would most likely set a de facto standard for data retention.

Ms. Wong said Google uses the search data internally only to improve its search engine and other services. She added that Google would release search data only if compelled by a subpoena. Even so, Google was the only major search engine to resist a Justice Department subpoena for vast amounts of search data last year — a move that drew praise from privacy advocates.

Just how personally revealing such data can be became evident last year, when AOL released records of the searches conducted by 657,000 Americans for the benefit of researchers. While AOL did not identify the people behind the searches, reporters from The New York Times were able to track down some of them quickly through their search requests.

The ensuing flap caused AOL to tighten its privacy policies. The company now keeps search histories for only 13 months and does not link them to Internet protocol addresses — digital tags that can identify a specific computer.

For its part, Yahoo keeps search data for “as long as it is useful,” said a spokeswoman, Nissa Anklesaria. And Microsoft said that while it does not keep search histories alongside I.P. addresses, it can connect the two if law enforcement requests it.

For Web companies, tying search histories to individuals or groups can be lucrative. Companies like Microsoft and Yahoo, for instance, use such information to customize the ads they display. While Google does not currently do this so-called behavioral targeting, some analysts believe it might do so in the future.

Google may be tightening its privacy policy around search logs, but the company recently relaxed its privacy practices in another area. Earlier this year, Google users who signed up for services like Gmail that require them to sign in started to be automatically enrolled in a service called personalized search. The service tracks a user’s search history and tailors search results accordingly. Previously, users had to specifically choose to enroll in personalized search.

Users can opt out of the personalized search service and delete their search history. Still, some analysts believe Google should give users more notice.

“I don’t know that a lot of people have realized that that kind of change has happened,” said Danny Sullivan, who edits the blog SearchEngineLand.com. “You can delete your search history at any time — if you remember.”