Updated
September 29, 2016.
Having recent backups of your files is crucial for any computer user; you never know when a crash or hardware failure can strike. A backup is especially important when you consider the investment of time and money you've made in your iTunes library.
No one wants to be faced with having to rebuild an iTunes library from scratch, but if you make backups regularly, you'll be ready when trouble strikes.
Backing up on your primary computer isn't a great idea. If your hard drive breaks, you don't want the only backup of your data to be on a hard drive that just stopped working. Instead, you should back up to an external hard drive or cloud backup service.
To back up your iTunes library to an external hard drive, you'll need an external drive with enough free space to contain your library. Plug the hard drive into the computer that contains your iTunes library.
Your iTunes library is a database that contains all the music and other media that you have purchased or otherwise added to iTunes. The iTunes library consists of at least three files: two iTunes library files and an iTunes Media folder. You need to consolidate all your iTunes files into the iTunes Media folder before backing up the iTunes folder to the external hard drive.