SAN FRANCISCO (AP) --

Twitter is offering a new way for advertisers to deliver their marketing pitches to the people who are most likely to buy their products and services.

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.

Twitter hasn’t disclosed how well it has been doing because it remains a privately held business. But the research firm eMarketer estimates Twitter will generate about $260 million this year. That’s well below other advertising-dependent Internet companies such as Google Inc., Yahoo Inc. and Facebook Inc. Google’s revenue this year is expected to approach $50 billion, while Yahoo and Facebook are expected to bring in about $5 billion apiece.

Like Twitter is doing now, Google, Yahoo and Facebook all collect data about their users’ interests in an effort to show them ads catering to their interests and preferences.

As it mixes more marketing message into the flow of people’s tweets, Twitter’s annual revenue is expected to more than double to $540 million in 2014, according to eMarketer.

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