A hub is used in a wired network to connect Ethernet cables from a number of devices together. The hub allows each device to talk to the others. (Hubs aren't used in networks with only wireless connections, since network devices such as routers and adapters communicate directly with one another, with nothing in between.)

Hubs are such simple devices — they require no configuration, and have no manuals — that their function is now included in other devices such as routers and modems. In the same place that hubs used to appear in networks, switches can usually be substituted. This will give better performance, and many additional features.

One hub feature for advanced users, is that, since all Ethernet traffic passes through all hub ports, a hub can be used to easily "sniff" a network, an advanced troubleshooting technique. Without otherwise reconfiguring the network, a hub can be inserted that will pick up all broadcast, unicast and multicast traffic A sniffer on a switch port will not see unicast traffic that's not going through that particular port.