Network - Virtual LAN (VLAN)
A virtual LAN (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2).
VLANs allow network administrators to group hosts together even if the hosts are not on the same network switch. This can greatly simplify network design and deployment, because VLAN membership can be configured through software. Without VLANs, grouping hosts according to their resource needs necessitates the labor of relocating nodes or rewiring data links.
To subdivide a network into virtual LANs, one configures network equipment. Simpler equipment can partition only per physical port (if at all), in which case each VLAN is connected with a dedicated network cable.