What is the hub on a bicycle?

bicycle hub

this is far from a complete answer, I've just started learning how to restore vintage bikes. But I know the hub is the circular metal peice that allows the tires to spin. It is in the middle of each tire where the spokes meet. I know this cuz I have a early 1930's Montgomery ward cruiser that needs a new back hub. hope that helps.

The Bicycle Hub the is the central part of a bicycle wheel it is circular and is connected to the spokes, at the bike hubs centre are bearings and this is where the spindle is fitted to allow rollling.