As search engines try to balance between wanting to dig into users' private information to improve their businesses and the consumers' and privacy groups' concerns over the risk of leaking confidential information, the battle of search engines is changing.

Major search engine companies are now competing partially based on how well they can provide privacy policies to protect users.

Microsoft announced Monday new policies and technologies, aimed at protecting users' privacy for its Live Search service. With IAC/InterActiveCorp.'s Ask.com, Microsoft will also announce plans to initiate an industry standard practice to retain the search histories of users.

Meanwhile, later this week, Yahoo! will detail its plan for a policy to make users' search data anonymous within 13 months, with the exception of users' requests, law-enforcement or legal processes.

Google also recently announced a plan to adjust the period it keeps users' search data, from a range of between 18 to 24 months, to 18 months maximum.