A device that allows to connect network devices together
Old device rarely used nowadays (Replaced by Switches)

It is also called Multi-Port Repeater as traffic that is received a port and is broadcasted to all devices connected to the Hub
Because of this devices that are connected to an hub can see each others packets
Hubs can lead to increased network errors (Large Collision Domain)

Hubs make use of Half Duplex Communication i.e. only one device can communicate at a time

Passive Hub: Repeats signal with no amplification
Active Hub: Repeats signal with amplification
Smart Hub: Active Hub with enhanced features like SNMP