Your Apple ID is the account you use for just about everything you do with Apple—including storing your content in iCloud; downloading apps from the App Store; streaming from Apple Music; buying music, movies, and TV shows from the iTunes Store; and purchasing books from the iBooks Store.
If you already have an Apple ID, use it to sign in when you first set up iPod touch, and whenever you need to sign in to use an Apple service. If you didn’t sign in during setup, go to Settings > Sign in to your iPod touch.
If you don’t have an Apple ID, you can create one anyplace you’re asked to sign in—for example, the iTunes Store, the App Store, and the iBooks Store. It’s best to have only one Apple ID.
For more information, go to the Apple ID account website.