What is Jailbreaking ?
Jailbreaking is the process that gives the user read/write access to otherwise locked OS files on their iDevice [iphone , ipod touch , ipad]. After jailbreaking a device , the user can get access to the root level of an iPhone or iPod Touch 4 which then allows them to run custom codes for installing new applications , like unlockers.
Benefits of Jailbreaking :
After you jailbreak iphone 4 , you can install any application installer like Cydia [very popular among jailbreakers]. Cydia comes with tons of apps like MyWi which lets your iPhone to convert into a WiFi host spot or My3g which can let you use face-time on 3G network instead of WiFi . A jailbroken iphone can be unlocked to access different carriers .
Is Jailbreaking Legal ?
Federal regulators announced last month [July 26th 2010] that it was lawful to hack or jailbreak an iPhone . However Apple is against it and has recently applied for a patent to remotely disable iphone's.
You said carrier unlock . What is that ?
Many mobile phone manufacturers software code their cellular device to work only with a certain operator . Such phones are called carrier locked. The process of unlocking iphone 4 will then allow you to use SIM cards of any operator of your wish . Iphone’s in the United States come carrier locked to AT&T which has the exclusive rights for iphone’s at the moment .