APNIC Google, Inc. This document updates the IP Version 6 Address Architecture to expand the size of the IPv6 loopback space from a single address to a /48 prefix, formally defined as Node-Local Unicast space. This change allows for a much larger number of loopback addresses and internal virtual networks within an IPv6 host, which can be used for inter-process communication, local virtualization, container networking, and diagnostics. This document updates RFC 4291 to define the prefix and its functional semantics, and updates RFC 4007 to specify how the prefix is integrated into the scoped address architecture. It also updates the IANA IPv6 Address registry, the IPv6 Special- Purpose Address registry, and the Locally-Served DNS Zone Registry.