Fact: Six of the top 10 most retweeted Twitter messages of 2010 were related to a musical artist. Fact: Eleven of the top 20 Twitter users with the most followers, including the top three overall, are musical artists. Truth: Clearly, there's an intimate connection between Twitter and music.

Today, five years after co-founder and then-chairman/CEO Jack Dorsey sent the first tweet on March 21, 2006-"just setting up my twttr"-Twitter has fundamentally altered the relationship between artist and fan, between label and fan, and between fans themselves. The ramifications of Twitter on the way music is discovered, marketed and sold have yet to fully materialize.

That's because word-of-mouth is the best, if most inefficient form of advertising. With Twitter, word-of-mouth now has structure and scale. It's traceable, trackable and potentially profitable. Twitter has become a beyond-massive broadcast platform-200 million registered accounts that contribute an average of 140 million tweets per day. It has raised more than $360 million in venture financing and is valued at more than $3.7 billion. But while Twitter's success in its first five years has been measured by its number of users and by traffic, the next five will be rated on its ability to turn a profit, and Twitter believes there is a real business opportunity in supporting the music industry.

"The more they can build an audience on Twitter, the more tickets they can sell, the more music they can distribute and the more of their core business model they will be able to support," says Twitter head of strategic sales Ross Hoffman (@hoff).

In the last year, Twitter started testing new programs and initiatives designed to make Twitter a more structured (and monetizable) experience for the brands and industries willing to pay for them, and hired new employees to manage these programs and teach celebrities and artists how to better use the service to their advantage. Among the early adopters are music companies like Interscope, Hollywood Records, Merge, Amazon and iTunes.

According to Omid Ashtari (@omid)-who joined Twitter in December from Creative Artists Agency as an entertainment business development executive and a sort of celebrity hand-holder-the most effective way to use Twitter as a promotional vehicle is through authentic communication directly between the artist and fan-regardless of risk. "It gives fans a feeling that any time, any day, the band can say something really fascinating," Ashtari says. "If you make people feel like they're missing out on something if they're not following your tweets, that's a great way to build demand."

Twitter's next step is to start making money. Partnerships with the music business play an integral role in that effort. Hoffman is leading the charge to create custom Twitter experiences for big brands willing to sponsor the experience.

"If a sponsor comes to us and wants to do some kind of deal involving music, we may approach labels or artists or management or venues and pull the pieces together," he says. During the Super Bowl, for example, it created a custom feed for the National Football League that aggregated all Twitter conversations related to the game in a widget that appeared on NFL.com, paid for and branded by Visa. Part of that included a graph of which topics and people were receiving the most mentions. Interestingly, the top five on the list that night were artists performing and appearing in commercials, rather than the players or the teams.

In April 2010, Twitter began testing a program called Promoted Tweets. Similar to Google's AdWords, participating brands can pay to have a tweet they create appear at the top of any search term with which they choose to associate it.

Interscope Records bought promoted tweets to market new releases from Lady Gaga, Maroon 5 and Taylor Momsen. On Feb. 28, for example, the label bought a promoted tweet to push the video premiere of Gaga's "Born This Way." Any Twitter search for the term "Lady Gaga" listed the Interscope tweet first, which included a link to the video on Vevo and encouraged retweets. The promoted tweet was retweeted 823 times in less than four days. Twitter estimates the marketing exposure for that one tweet was in the millions of eyeballs.

"That was a perfect example," Hoffman says. "It had a link to a video, a call to action, and encouraged fans to retweet it. A typical tweet might get 100 retweets." The campaign helped drive the video premiere to 2.7 million streams in 24 hours, according to data provided by Vevo.

Another program Twitter began experimenting with in 2010 is Promoted Trends. While the Twitter home page lists trending topics, Promoted Trends allows companies to buy a spot on that list for 24 hours at a time, marked as "promoted." It's different from Promoted Tweets in that it doesn't wait for users to search for anything. It just sits on the home page. The music industry was one of the first to participate in the program.

Both programs remain in the trial phase, and according to Hoffman are only offered to a handful of brands who "get it." This is in preparation for a widespread rollout. Hoffman says Promoted Tweets alone is seeing engagement rates of 5%-8%. This is massive compared with the typical 0.25% engagement rates common for Web banner ads.

Promoting music is one thing; getting people to buy is another, and Twitter's success in this area is inconsistent. On the positive side there are success stories like Durham, N.C.-based Merge Records and its use of Twitter to drive sales for Arcade Fire's 2010 Grammy Award-winning album, "The Suburbs."

A week after the album arrived last July, Merge used Twitter to offer the CD for $7.99 through the label's online store-a 50% discount, and even cheaper than the digital version of the album-through the Twitter accounts of Merge Records (18,000 followers), Arcade Fire (134,000) and Twitter Earlybirds (225,000). As a result, Merge sold more CDs from its online store the second week after the album was released than the first.

"Twitter has helped make music more democratic," Merge head of digital assets Wilson Fuller says. "That is, information about artists and releases is shared socially and not dependent on ad dollars spent for exposure." But, hip-hop artist Soulja Boy-despite having 2.5 million followers-sold only 13,000 copies of his album, "The DeAndre Way," in the week following its November 2010 release. And it wasn't like he didn't use Twitter to promote the album-more than 70 tweets were issued on the release day alone from his account, including links to iTunes.

To help provide better feedback, Twitter is testing an analytics dashboard that can provide artists with data on the number of tweets, retweets and other information sent on Twitter about them. It's currently offered only on a "situational" basis (meaning the artist or label has to have an existing relationship with Twitter to access it) but could wind up being another paid service down the line, although Twitter hasn't yet announced any plans.

But Twitter's power truly shines in the organic, unplanned successes that occur when fans start talking to each other about music they've heard, like or are interested in. It's an area that until recently has progressed naturally, first with users simply naming the songs they were listening to, then by including links to sources of that music and lastly by using third-party services like GetGlue or playlist-sharing services like ShareMyPlaylists that link to Twitter. That's inspired Twitter to get involved and start building new capabilities to make such sharing even easier.

"It's something that going forward we're going to try to do a lot more of because we feel one of the things we add value to is the ability to access music where it makes sense," Rdio chief technology officer/VP of engineering Todd Berman says. "When someone on Twitter says, 'Hey, check out this song,' you shouldn't have to leave Twitter to check out the song. You should be able to just listen to the song."

Amazon MP3 uses Twitter slightly differently. In May 2008, it began tweeting alerts on its Daily Deals for discounted music about once per day. It now tweets two to eight times per day and has amassed 1.5 million followers. Tweets include free songs of the day, artist samplers, playlists and links to songs by artists in the news related to events like the Grammys or the Super Bowl. "We received great customer response from the tweets," Amazon spokeswoman Cat Griffin says, "and continue to use Twitter as a way to update customers on their favorite artists and help them discover new music."

All this is just the beginning. Twitter has also started creating in-house services and applications first made popular by third-party developers, such as how it created its own iPhone app after several developers first created Twitter interfaces for the smart phone. In fact, it recently put new restrictions on developers using its API, warning them not to replicate any of Twitter's core functionalities in an effort to make the Twitter experience more "consistent" for users. At the same time, Twitter is working on providing more context around the short text sent in each tweet, which could include metadata embedded in tweets that tells users whether it's referencing a video or a song, or providing an easy-to-access guide to all the other conversations taking place around that tweet, all of which can be unpacked and expanded beyond the original 140-character limit.

Ultimately, however, Twitter's future success or failure depends on whether society at large-of which the music industry is only one element-can adapt to its tenants of sharing, transparency and openness-all in 140 characters.