iOS jailbreaking, or simply jailbreaking, is the process of removing the limitations imposed by Apple on devices running the iOS operating system through the use of custom kernels. Such devices include the iPhone, iPod touch, iPad, and 2nd Gen Apple TV. Jailbreaking allows users to gain root access to the operating system, allowing iOS users to download additional applications, extensions, and themes that are unavailable through the official Apple App Store. Jailbreaking is a form of privilege escalation, and the term has been applied to privilege escalation on other computer systems as well. The name refers to breaking the device out of its "jail",a technical term used in Unix-style systems, for example FreeBSD jail. A jailbroken iPhone, iPod touch, or iPad running
iOS can still use the App Store, iTunes, and other normal functions, such as making telephone calls.
Unlike rooting an Android device, jailbreaking is necessary if the user intends to run software not authorized by Apple. A tethered jailbreak requires that the device be connected to a computer each time it needs to be booted; an untethered jailbreak allows the device to be powered without computer assistance. Under the Digital Millennium Copyright Act,
jailbreaking iPhones is legal in the United States, although Apple has announced that the practice "can violate the warranty"
