What Does It Mean to Jailbreak an iPhone?

Question: What Does It Mean to Jailbreak an iPhone?
Answer:
In essence, jailbreaking your iPhone means freeing it from the limitations imposed on it by your carrier, whether that's AT&T or Verizon, and Apple. You install a software application on your computer, and then transfer it to your iPhone, where it "breaks open" the iPhone’s file system to allow you to modify it.

Why Would I Want to Jailbreak My Phone?

It lets you do everything from customizing the look of your iPhone to installing third-party applications (such as titles that are not authorized and available in the App Store) and customized ringtones on it. Depending on how far you're willing to go, you can do even more than that: Jailbreaking even lets you to unlock your phone so you can use it with a carrier other than the one from which you purchased it.