With the release of the RedSn0w iOS 4.2.1 jailbreak, the notion of tethered jailbreak has been reintroduced and there seems to be a little bit of confusion about what’s different between a tethered and untethered jailbreak.

I’ve seen many comments asking more clarification about what a tethered/untethered jailbreak is, so I thought I’d give you a quick and simple explanation…

Untethered actually means nothing to you. You can reboot your iPhone, turn it off and back on without any problem. Your iPhone will boot as it normally does. Everything will work properly on your iPhone.

Tethered means that for various possible reasons, you will have to use your computer to boot your device. At the time I am writing this, if you used RedSn0w 0.9.6b4 to jailbreak your iPhone 4 for example, you might have to use RedSn0w to start your iPhone every time you reboot it. If that’s the case, you have to launch RedSn0w, plug your iPhone in and select to “just boot tethered right now”.

A tethered jailbreak is obviously not convenient at all. I actually haven’t updated my iPhone 4 to iOS 4.2.1 yet for this reason (and the fact there is no unlock for the iPhone 4).

iPhone hackers such as Comex are working hard on a way to untether the iOS 4.2.1 jailbreak, so there is hope that you won’t have to deal with the whole tethered thing in the near future.