Difference Between LAN and WAN

¶ … conceptualize the networking process is with the open systems interconnection reference model (OSI). The OSI model proposes that networking will occur on seven layers, sometimes referred to as a stack. Those seven layers include the physical layer, the data link layer, the network layer, the transport layer, the session layer, the presentation layer, and finally, the application layer. Systems designers and operators both benefit from conceptualizing networks in this way. The physical layer of the OSI is exactly that, the hardware components.

Usually this refers to things like fiber optic network cables or Ethernet. Layer two includes the encoding of data into bits. Usually this layer can be divided into sub-layers like Media Access Control (MAC), which controls access issues and Logical Link Control (LLC), which handles synchronization issues. The third layer of the network is the layer at which IP and other routing protocols are handled. Addressing like IP addresses exist at this level. The transport level works at the host or end-user level to ensure complete data transfer.

Whereas the transport level deals with host to host data transfers, the fifth level, session manages application communications. Layer six is the point at which data is converted into recognizable file formats that are encrypted and sent across the network. The files we deal with regularly like JPGs can be visualized here. Finally, the application layer is the seventh layer. These applications should not be confused with those the session layer deals with.

Instead, the application layer is where the Web browser and other clients reside, for those final data transfers. Most consumers only experience this level of the network, although many will eventually have to explore other layers when troubleshooting their home or office networks. The primary difference between a wide area network (WAN) and a local area network (LAN) is that the latter is truly localized because it is constrained by geographic connectivity -- dependent on actual physical connections between systems. However, virtual LANs are possible.

A virtual LAN is not a WAN, though. A WAN can actually connect multiple LANs. The most well-known.