The pronoun who, in English, is an interrogative pronoun and a relative pronoun, used chiefly to refer to humans.
Its derived forms include whom, an objective form the use of which is now generally confined to formal English; the possessive form whose; and the emphatic form whoever (also whosoever and whom(so)ever; see also -ever).
What person or people; which person or people; asks for the identity of someone. (used in a direct or indirect question)
“Who is that? (direct question)”
“I don’t know who it is. (indirect question)”
What is one’s position; asks whether someone deserves to say or do something.
“I don’t like what you did, but who am I to criticize you? I’ve done worse.”
The person or people that.
“It was a nice man who helped us.”
Whoever, he who, they who.
A person under discussion; a question of which person.
What person or people; which person or people, as the object of a verb.
“Whom did you ask?”
What person or people; which person or people, as the object of a preposition.
“To whom are you referring?”
“With whom were you talking?”
Him; her; them (used as a relative pronoun to refer to a previously mentioned person or people.)
“He’s a person with whom I work.;”
“We have ten employees, half of whom are carpenters.”
what or which person or people
“I wonder who that letter was from”
“who is that woman?”
used to introduce a clause giving further information about a person or people previously mentioned
“Joan Fontaine plays the mouse who married the playboy”
the person that; whoever
“who holds the sea, perforce doth hold the land”
used instead of ‘who’ as the object of a verb or preposition
“her mother, in whom she confided, said it wasn’t easy for her”
“whom did he marry?”