Facebook debuts real-time ad retargeting service

Menlo Park, Calif.—Facebook Inc. has officially launched a real-time ad-bidding process, enabling advertisers to enter an ongoing auction for targeting ad space to Facebook users based on their browsing history outside the social site.

The new Facebook Exchange, previously tested in beta, allows advertisers to retarget Facebook users with messages, such as product offers, based on the websites they've previously visited. Marketers can bid in real time for these ads, which would appear on Facebook almost immediately after users' off-Facebook Web-browsing experiences.

Facebook Exchange offers bidding only on the social site's Marketplace Ads, displayed on the right-hand side of Facebook.com. The ads don't appear on mobile devices and are now offered only in the U.S.