Discussion:
VLANs can provide an effective way of separating network traffic into different broadcast domains, thereby improving performance and security when implemented properly. One common application is to segregate guest wireless traffic from internal corporate wireless and wired network traffic. Another is to separate one department's traffic from another, or to isolate certain types of traffic.
Search the Internet for examples of specific VLAN implementations. Does the performance improvement justify the investment? In the examples you encounter, is the security provided by VLANs adequate for the described application? What additional precautions should companies take to safeguard their internal networks and other guests?