IPv4 and IPv6 networks are not directly interoperable, which means that a transition mechanism is needed in order to permit hosts on an IPv4 network to communicate with hosts on an IPv6 network, and vice versa. The videos below will help you understand some of these techniques.
6in4 is a tunneling technique. You can manually set up a 6in4 tunnel. Watch this video to learn more.
6RD is a tunneling technique in which the IPv4 and IPv6 addresses come from the Internet Service Provider (ISP). Some ISPs offering DSL or cable services are implementing 6RD to connect their customers over IPv6.
NAT64 is a transition mechanism based on Network Address Translation (NAT) that makes it possible for IPv6-only hosts to talk to IPv4-only servers. NAT64 can be useful for mobile providers.
DS-Lite allows an ISP to give access to IPv4-only services for customers that have only native IPv6. This mechanism could be useful for DSL or cable providers.