Most but not all Laptop PC's can normally function as a large emergency power pack, able to provide charging to any USB device. They can do this even in power off mode.
This is a good way to charge your phone or tablet during travel.
The Laptop PC battery is available as a charging source. All you need to do is to plug your USB cable in to the correct port.
Here you see my HP laptop and the USB port. The port is marked with a flash sign in combination with the USB type (here a USB2 between the combined USB-eSATA and the DisplayPort port).
A similar feature is also sometimes available on newer stationary PC's.
