Twitter unveils new targeting tool for advertisers

The targeting tool introduced Thursday allows ads to be sorted into different categories of interest. Once an ad has been tagged under a specific topic, such as "dogs" or "animation," it could crop up among the tweets of users whose activity has indicated an interest in those topics.

Twitter also is allowing the ads known as "promoted tweets" to be tied to specific accounts that may have followers likely to have an interest in the subject of a marketing message.

The effort to sell more ads is part of Twitter's ongoing bid to capitalize on the popularity of its short-messaging service.

After it was founded in San Francisco in 2006, Twitter initially focused on making its free service as useful as possible to lure more people into sharing their thoughts and moments of their lives in blurbs limited to 140 characters.

Having established itself as one of the world's most important communications tools, Twitter has spent the past two years courting advertisers to prove it can also be a successful business.