Since Apple believes strongly in intellectual property rights, the designers included a unique feature in iPod: the player links itself to your iTunes database on one machine only. You can't take your iPod to work, or to a friend's, who also has iTunes, plug it in, and share your MP3s. The system reminds you that "Your iPod is linked to another iTunes database" and gives you the option to leave it that way or link to the new iTunes database -- at which point you will lose your MP3 files. While this is a great way to prevent MP3 theft, it could present a problem, should you want to use your iPod at work and at home.