This USB 3.0 cable connects your iPhone, iPad, or iPod with Lightning connector to your computer's USB port for syncing and charging. Or you can connect to the Apple USB Power Adapter for convenient charging from a wall outlet.
The cable is primarily used to charge the device. The iPhone and iPad both include a Lightning cable and a charger that is used to connect the USB end of the cable into a power outlet. The cable can also be used to charge the device by plugging it into the USB port of a computer, but the quality of the charge you can get out of your laptop or desktop PC will vary. The USB port on an older computer may not supply enough power to charge an iPhone or iPad.