Promoted Tweets are the first phase of the social network's attempt at monetizing a popular site that has been free of any semblance of ads since its 2006 start.
At the top of the stream of a search page you might see a related tweet from one of Twitter's first clients: Starbucks, Best Buy, Bravo, Red Bull and Virgin America. Ads are marked with "Promoted Tweet" highlighted in yellow.
Twitter is careful not to use the term "ad." In any interviews and the official blog, they highlight how the company already tweeted it, so it's an "organic" part of Twitter already. (It's an ad).
For a Promoted Tweet to show up, it must be relevant to the keyword and must "resonate" with users enough to be retweeted; otherwise, it goes away. The functionality is the same as a regular tweet.
Mashable has compared the ads to ones you've seen on Digg, because of the longevity and price attached to readers interacting with the ad.
If you've used UberTwitter and haven't visited the site recently, you'll be familiar with the ads -- "Sponsored Content" -- at the top of the replies and mentions of the mobile app.
Promoted tweets will show up in timelines at an unannounced date. Twitter is hyping the slow rollout of the addition of ads.
If you use another third-party Twitter client, such as HootSuite or TweetDeck, you might wonder what that means for you. For now, tweets are not being imported into these clients, but that might not always be the case.
At a Twitter's Chirp conference for developers Wednesday, the company announced it will split revenue from the Promoted Tweets with the third-party Twitter client if they chose to distribute the Promoted Tweets to their users.
It could be before next year, according to Ad Age.