Internet Protocol (hereinafter "IP") is the common communication protocol for all devices connected to the Internet.
Each device on the network identifies a communication target to connect to in order to communicate with each other.
A numerical label for identifying the target is called an "IP address".
Currently, we use IPv4 which was deployed more than 20 years ago. Now,
a problem of IPv4 address exhaustion is occurring and IPv6 is getting increased attention as a new version of IP.
Introduction: basic introduction of IPv6 (Japanese only)
@ IT IPv6: IPv6 technical information is explained (Japanese only)
All major Operating systems support IPv6 now. Windows started to support IPv6 from XP SP1 and Windows Vista is fully IPv6 compliant. For BSDKAME Project, and for LinuxUSAGI Project have provided support IPv6. For MacOS, an operation system based on BSD began to support IPv6 from OS X.
http://www.atmarkit.co.jp/fnetwork/tanpatsu/10winxpv6/winxpv602.html(Japanese only)
http://www.kame.net/
http://www.linux-ipv6.org/
Regarding IPv6 compatible communication services, a survey was conveyed in 2006. Services not only for corporate customers but for individuals were introduced.
https://www.v6pc.jp/pdf/H18ServiceResearchResult.pdf(survey results are available in Japanese only)