IPv6 is the proposed standard for IP addressing on the internet. The reason for creating the new IPv6 IP addressing scheme is because IPv4 does not provide enough IP addresses for the internet to be used by everyone. IPv6 addresses are 128 bits long and are written as 8 groups of digits rather than 4 groups of digits as is done with IPv4. IPv6 addresses are written as hexadecimal digits rather than numeric base 10 digits. The written IPv6 address is written with each group of 8 digits separated by a colon rather than a perios as with IPv4 addressing. IPv6 provides for up to 3.4×1038 unique addresses.
The 128 bits of the IPv6 addresses are split into a 64 bit network prefix and a 64 bit host address. The 64 bit host address is created using the Media Access Control (MAC) address of the networked device. An example of a valid IPv6 address is 3023:ac96:3561:9012:0957:ac78:6457:bce9
RFC 2373 and RFC 2374 describes IPv6.