LANS
Local area Network is a self-contained network that spans a small area, such as a single building, floor or room.
WAN
Wide area network is a network that spans a large area, often across multiple geographical locations.
GAN
Global area network is when a WAN includes sites and networks around the world.
WLAN
Wirless LAN is a self-contained network of two or more devices connected using a wireless connection. Spans a small area, such as a small building, floor or room.