A hub in an ethernet network is a multiport repeater. Hubs are most often used on networks usin UTP (unshielded twisted pair) cabling as the limit for this type of cable is 100 metres.

A hub will also divide the network up into a series of different sgments, thus reducing the likelyhood that a cable fault wil bring the whole network down. Hubs are commonly supplied with 12 or 24 ports, and are suitable for distributing a UTP cable to a room ot office full of network sections.

A hub also functions at the lowerst level of the OSI networking model, the physical layer.