Apple's iPod, iPhone and iPad range are arguably the industry standard for tablets and handheld devices, and with sales in the billions it is hard to argue against the quality of the systems. However, some are simply unhappy with the limitations that the vanilla operating systems of these devices provide. It has always been the approach of Apple to restrict the users' access to core files and settings; simplicity is part of the appeal for some buyers. The system does leave much to be desired for more experienced computer users. Hence why the Apple community have wormed their way into the core files and created software which opens up the internal firmware to edit to one's willing.
Programs such as Spirit and GreenPois0n, easily found at many sources online, are designed to allow even the most average of computer users the ability to break open the iOS firmware. It usually requires nothing more than connecting the device to a computer system via USB, activating the program and then waiting until the process has been completed. Upon restarting the Apple mobile device, users will find Cydia, heralded as the 'alternative' app store, where long lists of system extensions and additions can be installed. Even more can be added simply by inputting the database URL of other repositories not already included in Cydia's default listings. Restoring the device to factory defaults in iTunes wipes all of the jailbroken data and 'unjailbreaks' the device, meaning that the process is reversible at any point.
The disadvantages are few and far between, so it strikes me as odd that more Apple users don't unlock. With simple downloadable software available, it requires little technical prowess other than the basic understanding of the system and how to organise the new extensions. On the iDevice itself, the extensions and additions are organised in an app-like format; features can be turned on and off with the tap of a finger, and uninstalling couldn't be simpler. From my personal experience, the jailbreaking process is quick and simple, but customizing the device to your whim can be tedious as, while the Cydia marketplace organises jailbreak extensions perfectly fine, determining how each download will actually affect the system is harder to determine. Plus, to get your vision of a perfect OS assembled typically demands workarounds and system trickery. Crafting a unique system is no easy feat.
Not surprisingly Apple doesn't support such an outrageous violation of their terms and conditions. With most iOS updates comes the patching of certain exploits which are utilised by the jailbreaking tools, thus the community must gather and compose an alternative solution. This anti-jailbreak stance is remarkably peculiar if you look at the list of features officially added with each iDevice system update. Apple has a habit of not copying per ce, but taking inspiration from the feature/s which are the current incentives to jailbreak, even going so far as to offer to hire those who write jailbreaking software themselves. The question remains for those casual users about whether it is worth jailbreaking to get exciting new features early, but whatever the answer it is clear to see that the freedom jailbreaking these iDevices gives increases the value of owning one substantially.