so-and-so; someone (unspecified)
Used to refer to an unspecified person or people, similar to 'so-and-so' or 'someone or other'. Often used when the speaker does not know or does not want to specify the name.
who?; which people?
Used as a question word asking for the identity of multiple people, similar to 'who (plural)?' or 'which people?'. Less common than the singular 誰.
Who (all) is coming to the party?
I heard that so-and-so is coming, but I forgot the name.
There was a call from a Mr. So-and-so.
誰々が賛成したか教えてください。
Please tell me which people agreed.
Kana spelling is common in informal writing and when the kanji is not needed.
Alternate spelling without the iteration mark; less common but still used.
Reduplication of 誰 (だれ, 'who'), with the second character often replaced by the iteration mark 々.