VLANs are used to divide a physical network into logical network segments to control broadcast domains. VLANs create multiple virtual LANs within a physical LAN by using VLAN tags in the frame header to identify which VLAN each frame belongs to. VLAN trunks connect switches and route traffic for multiple VLANs by using the VLAN tags in frames to determine which VLANs the frames belong to and where to send the frames.