• by Mark Walsh  @markfwal, October 15, 2013

Facebook said it’s expanding its custom audiences ad offering, which allows marketers to retarget customers on the social network through their email addresses and/or phone numbers, by adding a feature that lets them also retarget people who visited their Web site or used their mobile app.

Facebook already allows businesses to retarget people on the site, based on their Web browsing habits through the Facebook Exchange (FBX). But Web site retargeting through custom audiences would extend beyond the desktop and aim more at small businesses and developers.

“For advertisers that have a large number of products and advertise to multiple audiences, FBX is the better solution. For businesses that don’t typically work with third parties, Web sites and mobile apps, custom audiences will allow them to show ads to people who have been to their site or mobile app and still utilize Facebook’s targeting abilities,” stated a Facebook blog post today.

A bike retailer, for example, could reach people who started building custom bikes on their site or through their mobile app, but didn’t make a purchase. Or a travel app might show ads to users that downloaded their app, but haven’t used it lately to prompt them to book a trip. 

Unlike FBX, Web retargeting in custom audiences wouldn’t require buying through a demand-side platform (DSP). Facebook is still testing the new capabilities for custom audiences and plans to roll out the expanded service globally in the next few months.