Comment by kidmin

Some minor/trivial corrections:

- gTLD stands for "generic TLD"[1], not a short form of global, comes from their "generic" usage. Both two categories of TLDs are in the domain namespace which is globally resolvable.

- Almost all of two-letter ASCII ccTLDs reflect the ISO country codes, from ISO 3166-1 alpha-2, but there are a few exceptions: the United Kingdom (GB) has ".uk"[2], Ascension Island (now part of SH) has ".ac", etc. (Yes, there are more non-ASCII ccTLDs: .新加坡, .УКР, etc.)

If you want to briefly take a look at how TLD registries structure their second/third level such as "k12.or.us" or "chiyoda.tokyo.jp", see "ICANN DOMAINS" section of the public suffix list[3] (note: it is not complete)

[1] https://icannwiki.org/Generic_Top-level_Domain

[2] https://cddo.blog.gov.uk/2022/11/15/is-it-time-to-retire-the...

[3] https://publicsuffix.org/