Twitter is promising that it can now "allow you to target your Promoted Tweets and Promoted Accounts campaigns to a set of interests that you explicitly choose." By targeting Twitter users' topical interests (from a list of 350 such interests), marketers can both connect with more users and deliver tailored messages. "When people discover offers and messages about the things they care about on Twitter, it’s good for both marketers and users." Twitter claims its ad products use a real-time interest graph to deliver relevant Promoted Tweets and Promoted Accounts to more than 140 million monthly active users. Marketers can reach them more broadly, or more precisely, through two methods of targeting.

First, for broader reach, is that marketers can target more than 350 interest categories (see graphic). For example, if you were promoting an animated film about dogs, you might select Animation (under Movies and Television), Cartoons (under Hobbies and Interests), and Dogs (under Pets).

To reach a more targeted set of users, you can create custom segments by specifying certain @usernames that are relevant to the product, event or initiative you are looking to promote. Custom segments let you reach users with similar interests to that @username's followers (but do not let you specifically target the followers of that @username). If you are promoting an indie band’s next tour, you can create a custom audience by adding @usernames of related bands, and so target users with the same taste in music. "This new feature will help you reach beyond your followers and users with similar interests, and target the most relevant audience for your campaign," promises Twitter.

This draws the inevitable Facebook comparison. As MediaBistro describes, Twitter’s targeting is unlike Facebook, which focuses on clearly identified audience segments—and that’s what makes Facebook ads successful. They reach an audience based on user-provided data like gender, age and Likes; Twitter does not ask for that data. "Twitter assumes," writes MediaBistro.

Yeah, but it’s a pretty good guess. As ClickZ describes, Twitter extrapolates users' interests from their public tweets; no they have not surrendered their gender or age info, but they have expressed a clear interest. "That data is already being used to aggregate custom data for each user in the discover tab," and to promote Twitter users they might want to follow based on similar interests. So targeting is simply putting that utility into advertisers' hands.

Here is a guess of our own, based on experience with Twitter's still-imperfect targeting precision. One of the brands that beta-tested targeting was Bonobos, a men's clothing line named after a species of chimpanzee. Bonobos held a 24-hour sale on Twitter and used targeting to achieve a not-bad engagement rate of between 1% and 3%. Our guess is that a good many of those targeted tweeters were zoologists or primate scientists.