USB2.0 cameras have a single USB2.0 Type B receptacle (port). The USB2.0 cable carries image data, power and control signals. The connector is compatible with standard USB2.0 interface cables.
You do not need to power down the computer to connect or disconnect a camera, nor do you need to reboot the computer after this is done.
In some cases, depending on the source or the USB2.0 hub to which the camera is connected, the USB2.0 interface may not supply sufficient power to the camera to allow normal operation. In these cases, the external power port can be used to provide power to the camera.