Before we discuss the difference between Untethered & Tethered Jailbreak lets talk a little bit about Jailbreak in general.What is Jailbreak? Jailbreak is the process that will free Apple iOS devices like iPhone, iPad, and iPod Touch from the limitations and restrictions imposed by the manufacturer, by giving the user access to the root command line of the iOS system. Once you have a jailbroken iOS device, you will have full control over customizing your device, adding themes, , teaks, add-ons,….etc
One of the advantages also for jailbreaking is that your device will have a new application called Cydia which will allow you to install thousands of third party applications, that are not available otherwise in the Apple app store.
Now going back to the main subject, there are two types of jailbreak, depending on the model of your device and your current iOS version, those two types are called Tethered Jailbreak and Unthread Jailbreak.
What is Untethered Jailbreak?
Untethered Jailbreak is the preferred jailbreak method because it requires no connection to your computer except for the 1st time that you jailbreak your device. You can reboot your device as many times as you like and your device will stay jailbroken. Even if your device loses power and you have to recharge it and turn it back on again, you will still have Cydia and your jailbreak status will stay active, without having to do any extra steps.
The down side about Untethered Jailbreak is, that its not always available. As Apple keep introducing new devices and also keep updating their iOS firmware version, developers must modify the jailbreak software so that it can support the new update, but because Apple keep improving their iOS security system, developers job to hack into the newer iOS is getting harder and harder, and ussually they will have to launch a tethered jailbreak for a while before they can launch the Untethered version.
What is Tethered Jailbreak?
In the other hand Tethered jailbreak will pretty much give you the same end results as the untethered jailbreak would, which is a jailbroken device free of limitation, but the main difference is that you will need to connect your device to the computer and run the jailbreak software and do a process called “Boot into Tethered Mode” every time your reboot your device, otherwise you will lose your jailbreak and Cydia.
As you can see thats why an untethered jailbreak is always a much popular options than tethered jailbreak. But for jailbreak lovers, something is better than nothing.