SAN FRANCISCO — Microsoft’s Bing search engine plans to drill deeper into Facebook’s social network and Twitter’s messaging service to showcase information unlikely to be found on Google.

The changes, unveiled Thursday, will reshape how Bing displays its search results. It represents Microsoft’s most dramatic shift in Internet search since the software maker introduced Bing as a “decision engine” nearly three years ago.

Microsoft Corp. is counting on the new format to loosen Google’s stranglehold on the lucrative Internet search market. In the process, Microsoft hopes to turn a profit in its online division, which has lost more than $6.3 billion since Bing’s June 2009 debut.

Bing replaced “Live Search,” a mostly futile attempt to challenge Google. Microsoft touted Bing as a Google alternative that would provide more meaningful results by helping people make important decisions, such as picking a doctor and finding the best time to buy an airline ticket.

For the past two years, Bing has been taking advantage of Microsoft’s close relationship with Facebook to make search results more personalized and more relevant to users. It’s an advantage Bing has over Google because its rival is shut out from the personal data Microsoft has access to on the world’s largest network. But Bing has failed to come up with an approach compelling enough to lure away most web surfers from Google.

Bing is trying to fix that with the latest changes, which come out next month. Microsoft plans a marketing blitz on television and the Internet to promote the changes. Anyone seeking a peek during the next few weeks of testing can go to http://www.bing.com/new Thursday to sign up for an invitation. The testing period will begin Tuesday.

The revised system presents Bing’s results in three columns, or panes.

The left column will feature the familiar blue links drawn from Bing’s computer formula for finding the most relevant results.

The middle section, called “Snapshot,” is reserved for completing tasks, such as getting directions, making a hotel reservation or buying movie tickets. This feature isn’t expected to be available during the testing phase.

The “Sidebar” column on the far right side will be the centerpiece of the new Bing.

Sidebar is where Bing users logged into Facebook will see recommendations culled from their Facebook network. From there, people will be able to pose questions for their friends on their own Facebook pages without leaving the results page. The results from a Bing search can even be shared on Facebook.