If that means nothing to you, then you’re clearly out of touch with the Europeans. For three years, they’ve been going crazy over Spotify. It’s a beautiful, polished, iTunes-like program that offers access to 15 million songs — according to Spotify, a bigger catalog than Napster’s, Rhapsody’s, MOG’s or Rdio’s (but there’s a footnote — see below). All the big record companies have signed on to this crazy experiment: Sony, Warner, Universal and EMI. (The usual “we’re afraid of the Internet” bands are missing, like the Beatles, Metallica and Led Zeppelin.)

The sound quality is excellent. (It’s 160-kbps Ogg Vorbis format, if that means anything to you.) The music starts playing almost instantly. With a click, you can share your playlists with friends on Twitter or Facebook, or see what they listen to most. A whole system of Web sites has cropped up where people can share, rate and recommend music and playlists.

And there’s one more big attraction. Let’s see ... what was it? Oh, yes — it’s free.

It’s true. For the first time in Internet history, you can now listen to any track, any album, right now, legally, no charge. No wonder it took a while to persuade the record companies.

Now, there are some restrictions. The big one is the ads: for two minutes of each hour you hear ads spliced in between your songs (usually for Spotify’s premium plans, described in a moment). And you see banner ads in the Spotify software. If you sign up now, you can listen to all the music you want this way for the next six months — but after that, you’ll be limited to 10 hours of free music a month.

The final footnote on the fantasy of free music is this: you need an invitation to join. That, obviously, is a speed bump intended to prevent Spotify’s computers from blowing up when 300 million hyperventilating Americans arrive simultaneously.