Twitter to start carrying ads

Brands including Starbucks, Best Buy, Red Bull, Sony Pictures and Virgin America will be the first customers for "Promoted Tweets".

Twitter raised more than $135m in venture funding last year at a $1bn valuation. But like Facebook, Twitter has been anxious not to upset its tens of millions of users round the world by overloading a site dedicated to personal communication with commercial messages.

"Stubborn insistence on a slow and thoughtful approach to monetisation -- one which puts users first, amplifies existing value, and generates profit has frustrated some Twitter watchers," wrote Biz Stone, Twitter's co-founder, on a blog post introducing the service.

He said Promoted Tweets was "non-traditional, it's easy, and it makes a ton of sense for Twitter". Twitter's real-time updates will make the ads "timely" and a "powerful means of delivering information relevant to you at the moment", Mr Stone added.

If enough users do not interact with a Promoted Tweet, by replying or forwarding it to their followers, the ad will disappear.

"We strongly believe that Promoted Tweets should be useful to you [as a user]," Mr Stone said. "We'll attempt to measure whether the Tweets resonate with users and stop showing Promoted Tweets that don't resonate."

Deals with Google and Microsoft's Bing search engine to put its real-time updates in search results last year have brought in enough money to make Twitter profitable on an operating basis. But, if successful, Promoted Tweets will be a much larger form of revenue that can grow with Twitter's usage.

Twitter has been talking for more than a year about introducing another revenue stream from professional accounts, with additional features such as multiple user names.

Promoted Tweets will allow brands to place a short message at the top of the list of search results when users look for information about a particular product, company or news event. The ad will be persistent so that it is not lost in the deluge of Tweets, with only one ad on each page of search results.

Advertisers will initially be charged on a cost-per-thousand basis, the traditional mechanism for online display advertising, but Twitter said it would also experiment with other payment models.

Potential advertisers could include news organisations, which have embraced Twitter as a means of breaking stories and attracting traffic, or brands that want to counteract criticism online as part of a crisis management strategy.

Twitter said it would allow Promoted Tweets to be shown on external software such as Seesmic and Tweetdeck, from which a majority of updates are posted.

Twitter's open platform has allowed many third-party services to spring up, filling needs not catered to on Twitter's own site. But Twitter has made such companies nervous by purchasing Tweetie, an iPhone application, and introducing its own software for BlackBerry smartphones, in direct competition with its "ecosystem".

Alberto Nardelli, founder of Tweetminster, a site for tracking British politics on Twitter, said that Twitter had many potential ways to make money. "I don't actually think that sponsored Tweets are by themselves a game-changer," he said. "You don't look at the model and go wow. My feeling is that the move should be seen within the context of Twitter experimenting with various revenue-generating possibilities."