(1) See 
Wi-Fi bridge.
(2) A device that connects two LAN segments together via infrared or microwave transmission.  A wireless bridge is often used to span buildings and provides a more economical method than laying cable or leasing a private line.  Long distance wireless bridges often require line-of-sight between transmitter and receiver; however, bridges used inside a home or building that add remote devices to a Wi-Fi network do not (see 
Wi-Fi bridge).
Spanning Geographic Areas
A wireless bridge is used to span buildings or areas where laying cable or leasing lines is prohibitive.
Securing Hotspot Access
A wireless bridge can also be used to secure a local wireless network that accesses the Internet via a public hotspot.  By wiring the bridge into the WAN port of the router, it serves as a gateway between the private encrypted network and the hotspot, which is not encrypted.