Over the past several years many have told me they are confused with iTunes; most of them are non-Macintosh users. So I decide to write this post in hope of giving, the many whom I have yet to speak to about this topic, some guidance. To understand how to work with iTunes you will first need to understand the terminologies associate with iTunes.
The music management application installed on your computer is called "iTunes". Within the application you have access to the "iTunes Store", where you can purchase apps for iOS devices, and depending on the country you live in, you may be able to purchase music tracks, rent or purchase movies and TV shows.
To access your iTunes Store account you will need an Apple ID. An Apple ID is initially created to be the same as your account's primary email address. Although you cannot change your Apple ID after it has been created, you can change the "Primary Email Address" for your Apple ID account as many times as you want. You can also add additional "Alternative Email Addresses" to your account after you have associated a "Primary Email Address".
If you do not know whether you have an Apple ID or if you want to create a new Apple ID, you can use Apple's web page to accomplish this. This is also one of the many places where you can change the "Primary Email Address" and default mailing address.
In the past music tracks purchased through iTunes are copy protected using Apple's own digital rights management (DRM) software, FairPlay. This DRM protection is enforced by the record labels rather than Apple. It is fortunate that Apple and the record labels were able to come to an agreement, which Apple announced on January 6, 2009, where they will no longer apply DRM protection to music tracks purchased from iTunes Store.
This DRM requirement is similar to the thinking record labels have behind restrictions place on Apple to prevent them from selling the same music tracks on all iTunes Stores around the world. Unfortunately the agreement Apple has with the record labels in 2009 does not remove the geographic restrictions on selling music tracks. That is why some iTunes Stores do not have a music section. The movie studios and TV networks also have similar geographic restrictions on Apple, therefore some iTunes Stores do not have movie and TV show sections.
Even though Apple removed DRM protection from their tracks sold through iTunes Store, if you did not upgrade your music tracks to the higher quality (192bits) AAC format of these tracks purchased prior to January 6, 2009, they will still be DRM protected. So to allow these tracks to be played on computers or one of the associated iOS devices, the copy of iTunes installed on the computer needs to be Authorized by the Apple ID from which the music tracks were purchased with. This requirement also applies to any purchases of iOS apps and movies.
Fortunately, iTunes allows itself to be "authorized" by multiple Apple IDs, and "authorizing" the iTunes on a computer is not the same as logging into an iTunes Store account, these are separate actions and doing either should not effect the other. It is also important to remember that the actual Apple ID of an account may be different from the "Primary Email Address".
The concept of Apple ID, iTunes and iTunes Store can be executed much better. It is definitely not one of Apple's best implementations. I hope this post becomes a start to help those working with their iTunes and accompany media.