The root bridge is an Aironet bridge that is located at the top, or starting point, of a wireless infrastructure topology. The root bridge is usually connected to the main wired backbone LAN. Since the radio traffic from the other bridges'' LANs will pass through this unit, the root unit is usually connected to the LAN that originates or receives the most traffic.
A non-root bridge is sometimes referred to as a remote or repeater bridge. It is a bridge that establishes a connection to the root bridge or another repeater bridge to make the wired LAN to which it is connected part of the bridged LAN.