Xenops wrote:what’s the overlap of usage between the three?
I don't know any percentages, but:
An uncomplicated way of thinking about it would be everyone uses traditional characters, but Mainland China swapped out about 2200 of theirs for simplified characters. There are over 50k characters, so even Mainland China uses mostly traditional.
But it’s actually more complicated than that. Characters evolve, and different languages borrowed characters at different stages. Some made their own characters too.
Most Japanese kanji match standard Chinese traditional, but they borrowed characters at several different times, so some are older versions and some even match simplified. They invented some of their own too (to be clear - I’m talking about kanji here, not kana).
Taiwan uses traditional, but they use different versions of certain characters.
Cantonese uses traditional, but they invented some of their own too. Also, they use a different combination of characters for many words, so you can’t just read traditional standard Chinese with Cantonese pronunciation and be speaking correct Cantonese, in case you were wondering about that.
Korean hanja is traditional, but borrowed a long time ago, so it’s pretty common to see slightly different versions of characters; when they differ, they are almost always a bit more complicated than standard traditional.
I know you didn’t ask about it, and it’s no longer used, but Vietnamese borrowed traditional characters long ago, and also made many of their own characters too. Standard traditional Chinese characters are normally used to convey both meaning and phonology, but sometimes just used for phonology, like in the case of some loan words. But in Vietnamese Chinese script it was very common for characters to have phonology without meaning. Even more so than Cantonese, you couldn’t just read standard traditional Chinese with Vietnamese pronunciation and hope to be understood.