Microsoft Corp.'s Bing search engine is increasing its emphasis on the recommendations shared within Facebook's online social network to give people something they can't find on Google's dominant search engine.

Starting Monday afternoon, Bing's search results will vary depending on whether the person making a request is logged into Facebook's online social network at the same time.

For example, Bing's standard ranking system might analyze a search request about the band "U2" and relegate a link pertaining to the music group to the fourth or fifth page of results if the query came from someone who wasn't logged into Facebook at the time. But that same link might appear at the top of Bing's first search page if the query were made by a logged-in Facebook user and a few friends in the requestor's social circle had pressed Facebook's "Like" button on the site.

Bing's revisions will also affect the rankings of some search results even when people aren't logged into Facebook. That's because Bing's formula also will consider how many times Facebook's more than 500 million members have pressed on a Web page's "Like" button to help determine the content's value and relevance.

"Bing is bringing the collective IQ of the Web together with the opinions of the people you trust most, to bring the 'Friend Effect' to search," Microsoft search executive Yusuf Mehdi wrote in a Monday blog post.

Bing also is adding several other features and tools that deepen its ties to Facebook. Among other things, online shoppers using Microsoft's search engine will be able to post links about products and services directly to their Facebook accounts to get the opinions from their friends and family. Microsoft plans to deliver notices about discounted travel deals on people's Facebook pages, based on the cities they have said they liked.

The changes are the latest step in a search alliance Microsoft and Facebook announced seven months ago in a joint challenge to Google Inc. Both Microsoft and Facebook are trying to lure traffic away from Google, the Internet's most profitable company, so they can make more money selling Internet ads.

Google, whose search engine processes about two out of every three Internet search requests, also has been trying to add more personal touches as Web surfers have bonded together on Facebook and other websites such as Twitter where they share photos, recommendations and other insights.

But Facebook's online hangout has erected barriers that prevent Google's search engine from indexing all the information on a social network where an estimated 30 billion pieces of content are being shared each month.

Facebook's antipathy toward Google became clearer last week when it acknowledged that it had secretly hired a prominent public relations firm, Burson-Marsteller, to persuade reporters and bloggers to write stories about Google's privacy problems.

Besides sharing a unified front against Google, Microsoft and Facebook also have financial ties. Microsoft owns a 1.6 percent stake in Facebook.

Microsoft also has teamed up with Yahoo in its quest to topple Google. Since last summer, Microsoft's technology has been powering Yahoo's search results. The Yahoo partnership has given Microsoft's engineers access to billions more requests to analyze in an effort to get a better understanding of what people are seeking based on specific queries.

Bing has been making progress, although it remains far behind Google and remains a financial drag on Microsoft, whose online division had suffered an operating loss of $1.9 billion through the first nine months of its current fiscal year.

Through April, Bing held a 14.1 percent share of the U.S. search market, up from 10.8 percent at the same time last year, according to the research firm comScore Inc. Google's share stood at 65.4 percent in April, a decline of less than a percentage point from last year.

"The appetite for Bing to experiment and take risks like this is much greater than Google's because it is still so much smaller," said Altimeter Group analyst Charlene Li.

As it deepens its Facebook relationship, Bing could rile some users who don't want or don't fully understand why their personal information is appearing in its search results.

"There is a thin line between helpfulness and creepiness," Li said.