Acronyms and abbreviations are different things though.

A not-untypical style (as used by the BBC) is to write initialisms like UUID in all caps, and acronyms like Nasa in title case.

Initialisms are pronounced by saying each letter in order. Acronyms are pronounced as if they were words.

"ID" is a funny case because it's an ordinary abbreviation, and not really an initialism* or acronym, but it's pronounced just like an initialism. I think I'd prefer it "ID".

I would definitely avoid writing it "Id", lest it be confused with Freud's concept.

* unless as Norm Macdonald joked, the "D" is short for "dentification"

“ID” can mean “identity document”, such as a passport.

This is, to my half American ears, bizarre prescriptivism. We pronounce NASA as “nasa” and UUID as “yoo-id” (and GUID as “goo-id). And ID is pronounced “eye-dee.” And of course we pronounce OK (short for “oll korrect”) as “okay.”

Is “yoo-id” a common way of pronouncing UUID? I’ve only every spoken each letter in turn.

I've only ever heard U-U-I-D, but I've also heard GUID pronounced as a single syllable like Gwid.

I don't know why we use `Id` for identifer, but that's consistent across our codebase and documentation (we may have missed a few spots, but that's an error on our part).

Not sure why it is inconsistent to have UUID be all caps and Id be title cased? They feel different to me. But maybe I'm missing something.