I have had a couple questions asking me about why iTunes is asking for credit card information when trying to download Ancestry.com's Tree To Go app when the app is free.
For those who are new to iTunes, it is required that you set up an account with Apple in order to download anything from the iTunes Store even if it is free. The reason why iTunes requires credit card information is so when/if you ever download something that you have to pay you will automatically be charged so you don't have to put in your credit card information every time. Even if you download an app that doesn't cost money you will still receive a receipt from everything you download. Your credit card will never be charged if you never purchase anything from iTunes.