Hubs

A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

In general, a hub is the central part of a network where all the devices come together. The term is familiar to frequent fliers who travel through airport "hubs" to make connecting flights from one point to another. In data communications, a hub is a place of convergence where data arrives from one or more directions and is forwarded out in one or more other directions. A hub usually includes a switch of some kind. (And a product that is called a "switch" could usually be considered a hub as well.) The distinction seems to be that the hub is the place where data comes together and the switch is what determines how and where data is forwarded from the place where data comes together.

Hubs are in some sense stupid devices, while Switches are smarter.  Hubs take the data and retransmit it across all ports on the network asking if the data belongs to them.  Switches keep track of what is connected to each individual port.  When data is received at the switch, the switch will forward it directly to that port.  This improves speed and connectivity, plus also adds a bit of security.