A computer network is classified by geographic scale. LAN, WAN, MAN, CAN and PAN are some examples. The two most important networks to understand are LAN and WAN.
LAN stands for Local Area Network. As the name implies, the network is geographically limited to one location. For example, a LAN is the network within your home. Your cell phones, smart home devices, computers and laptops are all typically connected under one network. In the business setting, an office building, storefront or a clinic would each have their own Local Area Network. The LAN allows connected devices to share data amongst each other. One device can communicate with another device within the same LAN.
WAN stands for Wide Area Network. Unlike a LAN, the Wide Area Network is not limited to one geographic location. The WAN is a larger network that encompasses more than one physical location. The WAN can comprise of individual geographically distinct LANs. For example, a healthcare system can exist in the New York region. The healthcare system consists of one hospital in Manhattan, one in Brooklyn and one in Long Island. Each hospital will have their own LAN. The LANs are interconnected to the WAN. The healthcare system is interconnected by the Wide Area Network. This allows for network communication between the individual LANs.
MAN stands for Metropolitan Area Network. A MAN is essentially a Wide Area Network but classified to a city.
CAN stands for Campus Area Network. Similar to the Metropolitan Area Network. A CAN is a WAN except specifically for a university campus or corporate campus. CAN is also referred to as Corporate Area Network.
PAN stands for Personal Area Network. The network is limited to personal devices, usually in close range proximity to the person. For example, a bluetooth headset and cell phone will be included in a PAN.