IPv6 or IP version 6 is the next generation Internet Protocol which will eventually replace the current protocol IPv4. IPv6 has a number of improvements and simplifications when compared to IPv4. The primary difference is that IPv6 uses 128 bit addresses as compared to the 32 bit addresses used with IPv4. This means that there are more available IP addresses using IPv6 the are available with IPv4 alone. For a very clear comparison, In IPv4 there is a total of 4,294,967,296 IP addresses. With IPv6, there is a total of 18,446,744,073,709,551,616 IP addresses in a single /64 allocation.