Do I need to buy a new sim card for iPhone 5?

I have the iPhone 4S and my friend is giving me her iPhone 5. Would I need to go to AT&T to get a new sim card or can I just put the old sim card from my iPhone 4S in it? Also, her iPhone is through a different carrier, I think Verizon. Would I still be able to use it even though I have AT&T?

You need to buy a new sim card. IPhone 5 uses a different sim card than the iPhone 4s. And you can only use a different carrier as long as she unlocked the phone.