I just recently got an IPhone and was wondering, If I buy an ITunes gift card and redeem it and then buy something off of the app store through my IPhone, will it take money out of my ITunes account to purchase them?
Or does it just get charged to my bill for whatever I buy out of the appstore?

Because I was wondering because I thought it did and went and bought one, and then bought some apps and it still shows in ITunes I still have all of the money there.

How did I buy these?