What does unlocking the iPhone do? Will I get in trouble for it?

I currently have an iPhone that is under AT&T. I want to stay with AT&T. I don't want to move to T-mobile, Sprint, Verizon, or anything else. I want to unlock it, just in case I'd want to use it overseas with another SIM card. If I were to unlock it on my own, would AT&T charge me anything? Would I automatically be kicked out of my contract and be forced to pay a termination fee of any sort? I don't plan on manually calling AT&T to end the contract, because I still want to stay with AT&T.

No.AT&T would not charge you a fee to unlock your iPhone because it is a GSM device, which means you can use it on basically any cellular network that accepts SIM cards.

No, You go to the apple store and pay then to do it. It will cost more than a normal mobile getting unlocked. It's around £50 to unlock an iphone and its around £10-15 for a normal phone.

If you contact the AT&T and get Unlock code or Unlocking service, AT&T will charge for that. But if you unlock it using other online unlocking sites you no need to pay for AT&T separately. You can just pay to online site for unlocking service and unlock it… Once unlock it you can use other network sim cards. But if you unlock it your contract finish. But you can also use AT&T sim… Visit the site http://www.wickedunlock.com/apple-iphone/rs11wp9/ get the remote Unlock service and unlock it from network lock easily.

No it is fine to unlock.