VLAN is a data exchange technology that logically divides local area network (LAN) devices (not physically, mind you) into segments (or smaller LANs), thereby realizing virtual workgroups (cells).

VLAN (Virtual Local Area Network) is the Chinese name for "virtual local area network". A VLAN is a logical group of devices and users that are not restricted by physical location, and can be organized according to function, department, and application, communicating with each other as if they were in the same network segment, hence the name VLAN.

VLAN is a relatively new technology that works at layers 2 and 3 of the OSI reference model. A VLAN is a broadcast domain, and communication between VLANs is accomplished through layer 3 routers. VLAN technology is more flexible than traditional LAN technology and offers the following advantages: Reduced management overhead for moving, adding, and modifying network devices; the ability to control broadcast activity; and improved network security.

Extended Information:

The purpose of a VLAN (Virtual Local Area Network) is very varied. By recognizing the nature of VLANs, it will be possible to understand exactly where their usefulness lies.

First, it is important to realize that 192.168.1.2/30 and 192.168.2.6/30 are different network segments that must be accessed through a router, and that any access to each other between different network segments must be through a router.

Secondly, a VLAN is essentially a network segment, and the reason it is called a virtual LAN is because it is a segment created under the interface of a virtual router.

Third, the purpose of VLANs will be described at the switch level.

Reference:Baidu Encyclopedia-Virtual Local Area Networks