ITunes traces its history back to 2000, when Apple(AAPL) bought an MP3 player system called SoundJam MP. Apple wisely turned that software into the far more user-friendly iTunes, which debuted alongside the first iPod in October 2001.
The iPod and its companion iTunes software plodded along without any serious traction for a year and a half until Apple released iTunes 4 -- the first version to feature the iTunes Music Store. It was also the first version to be available on Microsoft(MSFT) Windows, opening up iTunes to more than 90% of PC users.
Ten years later, nearly two-thirds of music sales around the world are purchased through iTunes. Apple's software has completely changed the music industry -- and not without controversy.
Apple doesn't keep screenshots of its past iTunes versions, but luckily the folks at OldApps.com are a bit more sentimental. They provided images to CNNMoney.