IPv6 can provide more addresses and support more networks than IPv4. For example, IPv6 offers enough addresses for every person on Earth to have 1 million addresses.
Because IPv6 offers a larger address space it offers improved scalability.
With 128 bit addresses, the larger IPv6 address space offers global access and scalability and solves the pending exhaustion of IP addresses.
Network Address Translation (NAT) is no longer required.
Flat address space and transparency are restored by IPv6 because NAT is eliminated.
Routing efficiency is improved due to the hierarchical network architecture.
IPv6 allows for hierarchical routing and effective route summarization.
IPv6 supports Auto-configuration.
IPv6 supports plug-and-play.
Enhanced support is included for mobile IP and mobile computing devices.
Addresses can be permanently assigned to end devices such as DSL, PDAs, mobile terminals and PCs.
Neighbor discovery (ND) replaces ARP in IPv6.
ND combines the IPv4 services for IPv4 Address Resolution Protocol (ARP) and router discovery.