If you've not heard anything about Spotify yet, know that you're going to be reading a lot about it over the next few months.

That's because Spotify could be the biggest thing that's happened to online music since the original Napster P2P client launched 10 years ago. And that's not even close to being an exaggeration.

Spotify is a free and legal PC and Mac-based music player similar to iTunes and Windows Media Player. The difference, though, is that you don't play locally-stored MP3 files in Spotify. You stream high-bitrate songs directly from the Spotify servers.

Click and play

You search for a song, band or album in the same way you would in iTunes (the interface is even quite iTunes-esque). You click it and it plays. And it all happens instantaneously. There's no waiting for songs to buffer. There's no waiting for your search to be sorted through. It all happens immediately - as if you're searching your MP3 library on your own computer.

And despite the fact that it's a fledgling service (you'll need an invite to try it out), the database of music is very impressive. While there is inevitably some music missing (you'll find the entire Queen back catalogue but no Pink Floyd) it took us quite a while before we started finding albums that weren't on there.

The pay-off is that Spotify is primarily funded through advertising. Every 10 tracks or so, you have to sit through a short radio-style advert (usually about 20 seconds). This may sound irritating - but really it's an extraordinarily small price to pay to be able to listen to almost any music you like - for free.

If you don't want any adverts between tracks, you can pay 99p for a day's ad-free listening, £10 for a month or £100 for a year.

Quick and easy

The Spotify application itself is extremely lightweight. It's a less-than 2MB download, which means it's extremely responsive, quick to load and it'll work well with old PCs.

And despite its dinky size, the app still has some fantastic functionality in it. For instance: you can create your own playlists in the sidebar just like iTunes. And you can then share those playlists with your Spotifying friends. Right click the playlist, and it'll have its own HTTP link. Send this to a friend, and when they click on it, your playlist will open in their own Spotify window.

You can send links to any song on the Spotify database in exactly the same way. It's brilliant. It's even got song-display integration with Windows Live Messenger just like iTunes et al.

So - is Spotify a genuine threat to services like iTunes? Or is this just a flash in the pan?

We think this could be big. Piracy has been the bane of music labels for a decade now - more and more people are becoming accustomed to getting their music for free.

A new approach

Labels can combat that by suing the pants of the worst offenders and by putting music prices down - or they can invent a new revenue stream and a new way of doing things. That is what the Swedish guys who developed Spotify did.

So it's not just the application that's exciting - it's the business model too.

Clearly it's not as simple as that, though. The MP3 generation is also the iPod generation - people want to take their music with them on the go. And obviously this is currently not possible with Spotify.

But that might not be a terribly big hurdle for ad-supported music services in the near future. Many MP3 players and phones these days come with Wi-Fi connections. So as they become more common, and public Wi-Fi points roll out in more towns and cities around the world, Spotify could be incorporated into portable music players and mobile phones.

Imagine this - you're stuck at the train station with only a phone and a pair of earphones. The next train is in 45 minutes and it's freezing cold. Wouldn't it be cool to load up a Spotify client on your phone, use the station's Wi-Fi connection to listen to any music you can think of in seconds - for free?

Financial plan

There is one final question that must be answered - is Spotify's business model financially viable? We think it is. There are currently not many banner adverts in the Spotify interface - we'd expect them to become more blatant in the future, though. And that will inevitably bring in more cash.

As previously mentioned, Spotify is invite-only at the moment. But we've got 10 invitations to give away. First ten people to email me get them!

EDIT: sorry, all gone :(

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