What are the iTunes library files?
Summary
The iTunes library is a database iTunes uses to organize your music. Two iTunes library files are created and maintained by iTunes for different purposes. They're both in the iTunes folder.
Products Affected
iTunes 7 for Mac, iTunes 7 for Windows, iTunes 8 for Windows, iTunes 8 for Mac, Windows
Mac OS X
/Users/username/Music/iTunes/iTunes Library
/Users/username/Music/iTunes/iTunes Music Library.xml
Microsoft Windows
\Documents and Settings\username\My Documents\My Music\iTunes\iTunes Library.itl
\Documents and Settings\username\My Documents\My Music\iTunes\iTunes Music Library.xml
The two different iTunes library files serve different purposes.
iTunes Library (iTunes Library.itl in Windows)
This file is a database of the songs in your library and the playlists you've created. Some song-specific data is saved in this file. If you delete the file, iTunes creates a new, empty copy when you open the application, but any playlists, song ratings, comments, or other information you created is lost. The iTunes Library file is only used by iTunes.
Note: The library file name for versions of iTunes prior to 4.9 was "iTunes 4 Music Library" for Mac OS X and "iTunes 4 Music Library.itl" for Windows. After upgrading to iTunes 4.9 or later, the older library files are moved to a "Previous iTunes Libraries" folder.
Tip: New versions of iTunes sometimes include enhancements to the iTunes library. When you open the new version of iTunes, iTunes upgrades your existing library to the new format and places a copy of the old library in the Previous Libraries folder. If everything goes fine during your upgrade to the latest version of iTunes, you can delete the older iTunes Library files.
iTunes Music Library.xml
This file contains some (but not all) of the same information stored in the iTunes Library file. The purpose of the iTunes Music Library.xml file is to make your music and playlists available to other applications on your computer. In Mac OS X other iLife applications (like iPhoto, iDVD, and iMovie) use this file to make it easier for you to add music from your iTunes library to your projects.
Important: Information about products not manufactured by Apple is provided for information purposes only and does not constitute Apple’s recommendation or endorsement. Please contact the vendor for additional information.