IPv4 is the current version of the Internet Protocol, the identification system the Internet uses to send information between devices. This system assigns a series of four numbers (each ranging from 0 to 255) to each device. IPv4 only allows for about 4 billion addresses and the Internet needs more room than that. IPv6 is the new version of the Internet Protocol and expands the number of available addresses to a virtually limitless amount–340 trillion trillion trillion addresses.
The Internet is running out of IPv4 addresses. Transitioning to IPv6 enables the Internet to continue to grow and enables new, innovative services to be developed because more devices can connect to the Internet.
Just like a phone number helps you communicate with another phone, an IP address (short for Internet Protocol address) is provided to your computer so it can communicate with websites, Internet services, and other devices. IP addresses are numbers that are displayed as strings of letters or numbers, such as 192.0.2.1 (for IPv4) and 2001:db8::1234:ace:6006:1e (for IPv6).
World IPv6 Launch on June 6, 2012, organized by the Internet Society, is the day participating major websites and Internet Service Providers (ISPs) permanently enable IPv6 and begin the transition from IPv4.
You don't need to prepare anything for IPv6; your applications and devices will work just as they did before. This change is to make sure you can keep using the Internet in the future just as you do today.
The complete transition to IPv4 to IPv6 will take time as every website and Internet Service Provider must make the switch. In the meantime, both systems will work together until IPv4 is no longer needed.
No, IPv4 services will continue to operate as usual.
You may be using IPv6 already, visit ipv6test.google.com to find out. Many devices you use already support IPv6; however, the websites you visit and your Internet Service Provider must first enable IPv6 before you can use it.
Many major websites and Internet Service Providers now support IPv6, but there are still many more who need to switch. If you'd like to use IPv6, contact your Internet Service Provider asking them to provide you with IPv6 Internet access. You may also need to enable IPv6 on your home router or upgrade to a home router that supports IPv6. For a list of home router manufacturers that support IPv6, start here.
Version 5 was reserved for the Internet Stream Protocol developed prior to IPv6–it was never widely deployed and will not be used publicly.