IPv6 is often called the next-generation Internet Protocol. It is designed to ensure ongoing end-to-end connectivity across the Internet. While workarounds have been able to extend the life of IPv4, they can create technical difficulties.
Broadly speaking, IPv6 is a conservative extension of IPv4. Most IPv4 transport and application layer protocols need little or no change to work over IPv6. However, IPv6 cannot be said to be 'backwards compatible' with IPv4 and so IPv6 is normally run in conjunction with IPv4 using dual stacking or translation techniques currently under development.
This co-existence between IPv6 and IPv4 is seen as a pragmatic step forward, and the immediate requirements are for transition planning and creation of organisational and national roadmaps.
Example of an IPv6 address:
The IPv6 address of www.ipv6.org.nz is 2402:6000:f001::50
IPv6 factsheet - ICANN website
Benefits that IPv6 offer Internet users:
Larger address space
IPv6 allows for practically unlimited IP addresses. IPv4's
4x109 (4 billion) addresses cannot provide every living
person with an address, let alone support the growing
market of connectivity devices, whereas IPv6 supports
3 x1038 addresses.
Header format simplification
The IPv6 header is a standardised format, simplified by
allowing headers to be chained together. There are only six
fields, the two 128 bit addresses for source and destination,
and no options. It is much more straightforward than the
IPv4 format; it produces simple headers when required, but
also allows for more complicated applications to add
intricacy.