IPv6-to-IPv6 Network Prefix Translation
IPv6-to-IPv6 Network Prefix Translation (NPTv6) is a specification for IPv6 to achieve address-independence at the network edge, similar to network address translation (NAT) in Internet Protocol version 4 (IPv4). It has fewer architectural problems than IPv4 NAT; for example, it is stateless, uses a 1:1 address mapping and preserves the reachability attributed to the end-to-end principle.
Source: Wikipedia — IPv6-to-IPv6 Network Prefix Translation (CC BY-SA 4.0)