The current version of IP is widely acknowledged to have many
shortcomings. To address these, the Internet Engineering
Task Force (IETF) has defined IP version 6[1]. Some of its features include:
Addresses are now 128 bits in total length, instead of 32 bits
in IPv4. This is a huge increase!
The address structure is hierarchical, but is much more
complicated than the simple "address class" used in IPv4.
Compatible with IPv4 for transition purposes.
Support for a variety of "service types", etc.
[2] Or, as it was
called during its development, IPng.