Tethered Jailbreak
Tethered jailbreaks are require a computer connection to boot a jail broken iOS device. It means this: every time your iPhone or iPod touch reboots or the battery dies, you have to connect (tether) your iOS device back to your computer so that the hardware can boot with the aid of the jailbreak application.After the device has been booted you can then disconnect it from your computer and use it as usual, just remember that if the battery dies or you reboot the iPhone/iPod you will need to connect it again.