After a week or so spent as the plaything of a select famous few, Twitter is now releasing their standalone music discovery app Twitter Music to the masses. At launch, the app is available on the web and on iOS only. It’s also only available in the U.S., the U.K., Canada, Ireland, Australia, and New Zealand right now. Twitter promises that further expansion is coming, including an Android app.

Ok, so what is Twitter Music? At its core, it’s a music discovery app that lets users find songs based on their own Twitter activity and the popular activity of others. Twitter says that it will “change the way people find music.”

“It uses Twitter activity, including Tweets and engagement, to detect and surface the most popular tracks and emerging artists,” says Twitter. “It also brings artists’ music-related Twitter activity front and center: go to their profiles to see which music artists they follow and listen to songs by those artists. And, of course, you can tweet songs right from the app.”

The app is broken down into four major sections: Popular, Emerging, #NowPlaying, and Suggested. All of them are about discovery. The Popular and Emerging sections simply display music that is, well, popular and emerging on the network. Pretty simple. The Suggested tab puts Twitter’s algorithms to work, recommending songs and artists using your Twitter data – who you follow, and who the people you follow follow. #NowPlaying lets you play music that has been tweeted out by people in your network who have used the #NowPlaying hashtag. That hashtag has been a popular one on Twitter for years, but Twitter Music is finally making it useful.

Once you find a song you want to listen to, you have a few options. If you have a Spotify or Rdio account, you can log into those and play the full song using your subscription-based service. If not, you can still listen to previews of track using iTunes. Early rumors of Twitter Music said that it wouldn’t launch with integration into a full subscription-based streaming service, but I’m sure we can all agree that it’s great that those were wrong.

Twitter says that they will “continue to explore and add other music service providers.”

The applets you follow artists, view their tracks, and tweet out what you’re listening to. The latter is especially important for the service as a whole, as the #NowPlaying aspect of the app is probably the most interesting.

Here’s what it looks like when you’re playing a track. Note the tweet button at the top right:

“Twitter and music go great together. People share and discover new songs and albums every day. Many of the most-followed accounts on Twitter are musicians, and half of all users follow at least one musician. This is why artists turn to Twitter first to connect with their fans — and why we wanted to find a way to surface songs people are tweeting about,” says We Are Hunted’s Stephen Philips. Twitter recently acquired We Are Hunted, a music discovery app, and they’re the ones who helped build Twitter Music.

As of this morning, Twitter Music is not yet up and running. The web app still says “coming soon” and the iOS ap has yet to appear in the App Store. But it will launch later today. We’ll let you know when that happens.

UPDATE: It’s live.