There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
The term open-standard does not cut it. People should start using “publicly available and sharable” instead (maybe there is a better name for it).
ISO standards for example are technically “open”. But how relevant is that to a curious individual developer when anything you need to implement would require access to multiple “open” standards, each coming with a (monetary) price, with some extra shenanigans [archived] on top.
IETF standards however are actually truly open, as in publicly available and sharable.
how about FOSS, free and open-source standards /s