In the early 1990s, internetworking wonks realized the world was not many years away from running out of Internet Protocol version 4 (IPv4) addresses, the numbers needed to identify any device connected to the public internet. Noting booming interest in the internet, the internet community went looking for ways to avoid an IP address shortage that many feared would harm technology adoption and therefore the global economy.
A possible fix arrived in December 1995 in the form of RFC 1883, the first definition of IPv6, the planned successor to IPv4.
The most important change from IPv4 to IPv6 was moving from 32-bit to 128-bit addresses, a decision that increased the available pool of IP addresses from around 4.3 billion to over 340 undecillion – a 39-digit number. IPv6 was therefore thought to have future-proofed the internet, because nobody could imagine humanity would ever need more than a handful of undecillion IP addresses, never mind the entire range available under IPv6.
The major problem with the IPv6 migration was the lack of a clear plan. We are now much better off since translation mechanisms are becoming more standard.
It kinda amazes me that CLAT still isn’t universally supported, e.g. Windows is only just getting it now.
Mobile adoption is pretty good on the other hand, a lot of the big providers went v6 only years ago without much issue (e.g. Telstra, my provider, went single stack v6 back in 2020.