Search engines - how well is your privacy protected?

The answers suggest that, based on the questions we asked, Ask.com was the most protective of user privacy. In fact, only Ask.com said it would not record what users type into its search engine. (Smaller search engines, including ixquick, said this as well, but we limited our survey to the five largest engines.) Ask.com also said it did not engage in behavioral targeting, which refers to the practice of offering advertisements based on previous searches.

And the rest? Results were mixed. Google avoids behavioral targeting, but after 18 months it performs a partial anonymization of users' Internet Protocol addresses--an action that's not terribly privacy protective. Google dominates the search market: 53 percent of U.S. Web searches in June were performed on its site, according to Nielsen/NetRatings.

Microsoft is better on the anonymization front. Peter Cullen, the company's chief privacy strategist, said users' Internet addresses and cookie values are "permanently and irreversibly" disassociated from the search terms after 18 months. But Microsoft does engage in behavioral targeting, while Google doesn't. Yahoo and AOL were similarly mixed.

These were, nevertheless, remarkable improvements. Google, Microsoft and Yahoo told News.com, in response to an earlier survey we did in February 2006, that they kept search records for as long as the data prove useful. Now they've set expiration dates, and Ask.com went further by promising to stop recording user search histories starting later this year. Google also has shortened the lifespan of its cookies from expiring in 2038 to expiring two years from the last visit.