Introduction
Jailbreaking an iPhone is a task commonly performed to remove the software lock that Apple put in place to prevent the use of non-approved software. Normally, each piece of software or file used on the iPhone must be downloaded and approved through either iTunes or the App Store. With an unlocked iPhone, the user is allowed to bypass this restriction and gain access to the thousands of free, third-party applications available for the iPhone.
do it
Jailbreaking is fairly easy. A free program is downloaded to the computer, the iPhone is plugged into via the USB cable, and the program is run. Usually, a "restore" is recommended before jailbreaking. This ensures that the phone is "clean" and that nothing interferes with the jailbreaking process. There are specific steps that must be performed during the jailbreaking process, such as locating bootloader files and holding down buttons to enter DFU mode. The whole process usually takes about 10-15 minutes. A jailbreak can be "undone" by restoring the iPhone through iTunes.
Types of programs available
Software developers generally develop applications that take advantage of an iPhone feature that was disabled by either AT&T or Apple, like multimedia messaging (MMS) and Internet tethering to a laptop. Custom iPhone themes are also popular, as are game console emulators. Other programs add functionality to the operating system, like multitasking, memory management and media players.
Fears of jailbreaking
Many iPhone users are hesitant to jailbreak their phones because it voids Apple's warranty. While this is true, restoring the phone through iTunes will reverse a jailbreak and restore the factory settings, leaving no evidence behind. Some users are also afraid that they will "brick" their iPhone during the process and be left with nothing but an Apple-branded paperweight. These fears are unfounded--if something goes terribly wrong, in almost every case the iPhone can be put in DFU mode and then restored through iTunes.
Tags: through iTunes, jailbreaking process