The term iphone jailbreak refers to removing the limitations on Apple devices running the iOS operating system through the use of software and hardware exploits. Devices with iphone jailbreak include the iPhone, iPod touch, iPad, and second generation Apple TV. iphone jailbreak permits root access to the iOS operating system, allowing the download of additional applications, extensions, and themes that are unavailable through the official Apple App Store. iphone jailbreak is said to be a form of privilege escalation. Term iphone jailbreak has been used to describe privilege escalation on devices by other manufacturers, too. The name iphone jailbreak refers to breaking the device out of its so called jail, which is a technical term used in Unix-style systems. After an iphone jailbreak the iPhone, iPod touch, or iPad running iOS can still use the App Store, iTunes, and other normal functions, such as making telephone calls.
Restoring a device with iTunes removes the iphone jailbreak. One of the main reasons for the use of iphone jailbreak is to expand the feature set limited by Apple and its App Store. Apple checks apps for compliance with its iOS Developer Program License Agreement before accepting them for distribution in the App Store. And an iphone jailbreak permits the downloading of programs not approved by Apple.