More than 1.5 years after acquiring the Atlas Advertiser Suite from Microsoft, Facebook today relaunched the service in a bid to expand its advertising reach across the Web.

The service essentially allows advertisers to tap into Facebook's collection of users to direct ads at people via other websites and mobile apps, creating a new revenue stream for Facebook.

"We've rebuilt Atlas from the ground up to tackle today's marketing challenges, like reaching people across devices and bridging the gap between online impressions and offline purchases," Atlas head Erik Johnson wrote in a blog post.

Today's ad measurements rely heavily on cookies—data files stored on your computer to keep track of movements within websites. But the technology, according to Johnson, is not enough to sustain modern marketing campaigns.

"Cookies don't work on mobile, are becoming less accurate in demographic targeting and can't easily or accurately measure the customer purchase funnel across browsers and devices or into the offline world," Johnson explained.

Advertising firm Omnicom is the first holding company to partner with the new Atlas.

"We know that 65 percent of all shoppers use their mobile devices while out shopping, but, unfortunately, cookies don't work—or don't work well—on mobile devices and thus fall short when accompanying a customer on a shopping journey," Omnicom CEO Jonathan Nelson said in a statement.

"By reaching all the way from contemplation of purchase to the actual point of sale, Atlas is a compelling new offering for Omnicom's clients and their brands," Nelson said.

The Facebook-owned service will also collaborate with a handful of other organizations—search, social, creative management, publishers—that bring people-based measurement to more channels.

Instagram, for example, is enabled with Atlas to measure and verify ad impressions, Johnson said. Those Atlas users already running campaigns through the photo-sharing site will automatically see Instagram ads in their reports.

Microsoft snagged Atlas in 2007 as part of its $6 billion purchase of aQuantive, and was trying to sell it for years. Around the same time, Redmond paid $240 million for a stake in Facebook.

For more, see Facebook Nails Advertising, But Can It Sell Actual Stuff? Also check out How to Stop Facebook From Sharing Your Web Browsing History.