iTunes library primarily consists of two files, the Library.itl which is the database of all the songs present in your library and the Library.xml which contains information about the content of your library. The Library.xml file plays another important role as it allows third party apps to import information about your iTunes library (playlists, tracks...).
Since the 12.2 update iTunes no longer create the .xml file and this tutorial explains how to get it back. You can enable or disable the sharing of this file with other applications using the below procedure:
Open iTunes. Click on the Menu button > Preferences:
Go to the Advanced section and tick the Share iTunes Library XML with other applications:
Click on Ok to validate. The Library.xml will be create in: Users/username/Music/iTunes