IP version 6 (IPv6) is a new version of the Internet Protocol, designed as the successor to IP version 4 (IPv4) [RFC-791]. The changes from IPv4 to IPv6 fall primarily into the following categories:
Expanded addressing capabilities
Header format simplification
Improved support for extensions and options
Flow labeling capability
Authentication and privacy capabilities
For more information on IPv6 in general, visit the IETF's IPv6 Working Group.