There is a finite amount of them - 2^32, some 4.3 billion - the limitation stems from using 32-bit values to express them. We cannot have more added, as the "capacity" of the 32-bit IP address value to provide different numbers has been exhausted by "assigning" these blocks of IP space - back in the old days of the Internet, large blocks of IP space were given to large organizations (such as Xerox mentioned in the article), now cloud hyperscalers are buying them back at a premium so their customers can use it to host things.

Because there are only 4.3B of them possible, and we've not done the best job of migrating to IPv6.

Said another way, AWS owns approximately 3% of all IPv4 addresses.

I understand that they are limited, but that doesn't explain why are they sought after?

Essentially, how are they better than IPv6 addresses?

Only approximately 45% of clients support IPv6. Clients that don't support IPv6 can't talk to IPv6 servers. Depending on your target market, that might be as high as 70% (India, France) or as low as 0.2% (several african countries). Today most of these devices will have some form of IPv4 connectivity, though it's often through NAT, which is slower and problematic for P2P like games.

https://www.google.com/intl/en/ipv6/statistics.html#tab=per-...

Thank you for the short but clear explanation.

The main reason is they "just work" and they're now a scarce resource.

Having something that's addressable on the internet is trivial when you have a public IPv4 address.