A jailbroken phone is typically an iPhone® modified to let the user install applications that are not released through Apple®'s "App Store." The term “jailbroken” can also be used to refer to iPods and other devices that have been modified for similar reasons. This practice is not condoned by Apple®, which regards it as copyright violation, and it voids the warranty on the phone; if the phone is damaged or the software is corrupted, then the user has no recourse through Apple®. As of 2012, the practice of "jailbreaking" a phone is not illegal, and a number of companies and programs provide jailbreaking as a service.
Purpose and Functionality
Jailbreaking is not the same thing as unlocking a phone. When a phone is unlocked, it means that it can work on any mobile network. A jailbroken phone, on the other hand, specifically lets the user install applications from sources outside the App Store. It is typically a software modification that does not physically alter the hardware of the phone, and can be done by downloading jailbreak software.
Process for Jailbreaking
iPhone® owners can use numerous online guides to produce a jailbroken phone, with varying degrees of reliability. People who are not experienced may encounter problems following such guides, and they could damage their devices and render them unusable. The process for jailbreaking varies depending on which version of the phone someone owns and the software version installed onto it, making it important that a user reads the instructions thoroughly before starting. Mistakes made while jailbreaking a product can corrupt the software on it and make it impossible to use without repairing the issue.
Negative Consequences
Sites providing information about iPhone® hacks, such as those that produce a jailbroken phone, usually come with extensive disclaimers warning users that they proceed at their own risk. Users typically cannot take a jailbroken phone into an official Apple® store for service or repairs, and they may have difficulty updating the software on such a device. Those who lack expertise in this area may want to avoid trying to jailbreak their phone or other devices, to ensure ongoing service. While Apple® considers jailbreaking a violation of copyrights on the phone software, it is not illegal in the US and many other countries and only violates Apple®'s warranty for service and repair.
Background
Almost as soon as the iPhone® was released, Apple® was criticized for forcing users to go through their App Store to access applications, and for restricting applications available through it. Apple®'s defense of the store was that it ensured all applications loaded by users onto iPhone®s were safe for use, reducing the risk of spreading viruses or corrupting the software. Critics pointed out that applications that rivaled Apple®'s products were not available, even though many were safe for use, while some critics simply disliked the idea of being told what they could and could not download. As a result, shortly after the iPhone®'s release, people were jailbreaking their devices and providing information to others who want a jailbroken phone.