Hubs
A hub is a generic connection device used to tie several networking cables together.
Hubs that are plugged into electric power amplify or repeat signals and are called active hubs. These hubs are also known as multiport repeaters.
A hub that provides no signal regeneration is called a passive hub and is not a repeater.
If a hub segments or subdivides network traffic it is an intelligent or switching hub.
A star topology often has a hub at its center.