In 1981, computers with Internet access were only a part of military or research organizations. In this 8-bit environment, the 32-bit address space offered by Internet Protocol version 4 (IPv4) seemed unlimited, allowing nearly 4 billion possible addresses (2 to the 32nd power) for connected devices.
Now-a-days a lot of people can connect with computer.So in theory, no new device can be attached to the Internet. In 1998, ICANN(the Internet Corporation for Assigned Names and Numbers) ratified a new Internet Protocol, IPv6. It shifts to a 128-bit IP address space (each broken into hexadecimal groups), which means around 340 undecillion (340 times 10 to the 36th power) possible addresses, or billions of addresses for every living person.
This expanded space is critical for the continued growth of the Internet.
IPv6 benefits will include a level of security baked into the protocol.
IPv4 was designed for an “age of innocence” with a small Internet population.
It should become harder, for example, for criminals to use “address spoofing” attacks, where Websites or e-mail messages misrepresent where they come from.
IPv6-era routers and firewalls will provide greater protection against anonymous attacks.
In addition, IPv6 will enable finer control of how rich media and critical applications perform on a network, and allow faster transactions over virtual private networks (VPN). It can boost VoIP or unified communications services
A VoIP conversation or video Webcast on your network, for example, would get priority over a file transfer.