Hub

A hub is the part of a wheel that connects the wheel to its axle.

Technology
Ethernet hub, connects all the cables in a Local Area Network
Port multiplier, a component in Serial ATA
USB hub, allows connecting to many devices to a single USB port

Transport
Transport hub or transport interchange is a station which allows to switch between different lines in the transport network.
Airline hub, an airport used by an airline as a transfer point

Places
Hub Tehsil, a tehsil in Pakistan
Hub, Balochistan, the capital of the tehsil
Hub River, a river in Pakistan

Others
In video games, a hub is a special Level which connects to many other levels.
The Hub (TV channel), a television network in the United States