Back in July, Twitter (News - Alert) was said to be working on a concept known as retargeted ads, a concept that stayed experimental for some time. Driven by browser cookies and using Twitter accounts as a kind of identity layer that could allow Twitter to offer up very specific ads on mobile devices based on where users go online, the program has been officially confirmed at last report, and is set to make its play fairly soon.

Some of the details behind Twitters new advertising program, meanwhile, are a bit unclear. Reports suggest the retargeted ad campaign is set to emerge in a “soft launch” style event, which means that availability will be tight for at least a while, and some advertisers simply won't be able to get in on the action. Some users may never see such ads, either, and thus the concept of retargeted Promoted Tweet advertising is, at best, up in the air. There's also no word on if email address retargeting will get a comparable expansion, and on these points, Twitter is staying mum.

Basically, with retargeted ads, Twitter is looking to use a user's browser history to figure out which ads would be best to present at any given time. Here, of course, “best” means “most likely to pay attention to and interact with,” which is just what advertisers are looking for. That's a fairly big step, though one competitors like Facebook (News - Alert) have already been looking into and working with. Where Twitter distinguishes itself here, however, is in the fact that it's using retargeting in mobile advertising, something Facebook has been more hesitant about doing.

Given that 70 percent, at last report, of Twitter's ad revenue comes from mobile (which suggests that mobile is where the bulk of Twitter's users and engagements come from), implementing retargeting on mobile devices makes quite a bit of sense. But since phones and tablets don't much use cookies, this has posed a problem for retargeting efforts...until now.

Twitter has users across several different types of devices, including those devices that use cookies. With this point in mind, Twitter can then bring in retargeting by connecting the cookie list on a cookie-using device to a Twitter account, then keep that information in play when users hit a mobile Twitter.

While this may sound creepy, it's actually fairly humane; most of what Twitter users do is done in public, so privacy concerns are slim. Twitter also offers opt-out capability, and honors Do Not Track for those users who actually use it at the browser level. Even the Electronic Frontier Foundation has had some due kudos for Twitter's tempered use of tracking and its available protections – something that's not exactly frequently seen.

Twitter – as with all social media – lives and dies by its user count. The sheer number of users it can bring to bear is one of the biggest selling points it can make to advertisers and investors alike, and with its IPO recently concluded, there's still some selling to be done on both sides. While the sheer bulk of users is important, a service that can make advertising to that bulk more effective only increases Twitter's value as an advertising platform. Retargeting can help do just that, and this should make Twitter a top destination for advertisers, especially those who want very specific advertising impact.