This provides enough capacity for an estimated 340 undecillion IP addresses, one for every grain of sand on the planet. So, IPv6 can accommodate a much larger number of devices and includes features such as authentication and multi-casting, which have been bolted on to IPv4 over the years. In general, however, IPv6 has retained as much as possible of IPv4 without compromising on the goal of extending the life and improving the usability of the Internet. Work on IPv6 has been underway since the early 1990s, and much progress has been made. The core set of IPv6 protocols became an IETF draft standard in 1998.
Minor changes are likely, but no major ones.
IPv5 never really existed. Although ST was never widely used, the decision was made not to reassign the number 5. So, IPv6 was born. Now there is even talk of developing the Internet in even-numbered increments. They already are.