MP3 is the most ubiquitous music format in the world, but when you purchase and download a song online it rarely comes in that format.
That's because the MP3 format is free and open, and record companies typically demand more control than that.
So purchased music tends to arrive in more obscure DRM formats that provide record companies with firmer control.
Unfortunately that usually also means that the end listener has less control over the music they've purchased.
Typical headeaches include being unable to play a song on a desired device, or losing the license to the song (which renders the music file useless).
Luckily there are a couple signs that this unfortunate phase in music history may be coming to an end:
Recently Apple has added an impressive new DRM-free section to their iTunes store named "iTunes Plus".
My only complaint is that most of the songs in these DRM-free selections seem to be from decades gone by.
Don't get me wrong, I love Pink Floyd - Dark Side Of The Moon as much as the next guy, but it would be nice to have more current songs in the mix as well.