Tunneling is a method used to encapsulate IPv6 packets within IPv4 packets to allow IPv6 packets to be sent over IPv4 networks. This mechanism is essential for the coexistence of new and existing network infrastructures during the transition period from IPv4 to IPv6. NAT64 modifies IPv6 packets to IPv4 packets, but it does not encapsulate them. Dual stack involves running IPv4 and IPv6 in parallel on the same device and does not describe encapsulation through an IPv4 network. VLAN is a completely different technology used to segment networks into smaller parts within a Layer 2 network and does not facilitate IPv6 to IPv4 communication.