USB hub
A USB hub is a normal USB device, which was built for a given version of the standard. Certain models may support different versions of USB, while others may not.  As an example: USB 3.0 can transfer payload data at up to 4 GBits per second. USB 2.0 is limited to a transfer rate of 280 MBits per second. Connecting an USB 3.0 device to the computer using an USB 2.0 hub will limit the transfer rate to that of USB 2.0.