A USB hub is a device that turns one USB port into multiple downstream ports, letting several peripherals share a single connection to a host computer. It carries both data and power, so it is part of the trust boundary between the machine and whatever is attached to it.
In cyber security, hubs matter because they can affect device enumeration, power delivery, and the visibility of attached hardware. A cheap or opaque hub may hide poor controller quality, firmware bugs, or unsafe power handling. In attacks, a hub can serve as a convenient insertion point for rogue peripherals or additional hidden circuitry. In defenses, teams inspect hubs to verify behavior under load, check for unexpected devices, and reduce the risk of unstable or untrusted hardware entering sensitive systems.