Why do you have to give a credit card number to use itunes gift cards?

I don't have an account on itunes, but when I tried to use my itunes gift cards, it made me create an account and it asked me for my credit card number. Why do I have to give my credit card number to use gift cards? Will it charge me?
Okay, thanks guys
I got it working.

Don't enter your credit card #, it should give you the option of entering it or redeeming a card. If it doesn't- download the newest edition of iTunes. With a gift card you don't have to enter your credit card info with the new edition.
you dont need to just leave that part blank i put mine on yeaterday i had that problem too
its only asking you for your credit card because it thinks your gonna buy songs from itunes
but since you have the giftcard
just leave it blank
just b/c everything duz that and in case you go over your balance.
i dont think you HAVE to submit it.
i never had to…..
It will not charge your credit card, it just asks because the iTunes store wants to know what to charge if you go over your limit of the giftcard. Hope I helped!!!!
You do not need a credit card to use your iTunes gift card.