How does a USB hub work?

The USB   h ub is used for device expansion connection, and all USB   d evices are connected to the ports of the USB   h ub. One USB   h ost is always connected to one r oot   hub . The USB   h ub provides 100mA to each of its ports for devices to use. At the   same time, the USB   h ub can diagnose the plug-in operation of the device through the electrical changes of the port, and report the port status to the USB   h ost by responding to the data packet of the USB   h ost. Generally speaking, the cable length between a USB device and a USB   hub cannot exceed 5m, and the USB system cannot be cascaded  to   more than 5 levels(including the r oot   h ub).                                           (Picture Source:  Multiport Adapter 3.0 Type C Hub ) Each downstream interface of the USB   hub will equally ...