When do you use "who", and when do you use "whom"?

Answer 1

The way I remember it is if you can replace the word in question with "him" (or "her"--but "him" ends with M so it's easy to remember) then you should use whom, and if "he" (or "she") works, then it's generally "who"

"I should give this to whom?" (because you could say "I should give this to him?" not "I should give this to he?"), or "Who wants this?" ("He wants this?")

Answer 2

You use who when you are using it as a subject of the sentence. Whom is used as a direct object in a sentence.
i.e. Who are you? (who is the subject in the sentence)
Who is that girl?

To whom will I give this book? (whom now is the object in the sentence - )
Whom did you appoint to do this?

Notice if you answer the questions. Who will be the subject and whom will be the direct object.

Answer 3

Who” and “whoever” are subjective pronouns; “whom” and “whomever” are in the objective case. As simple and important as that distinction is, many people have difficulty deciding on the proper usage of “who” and “whom” in sentences.

Examples:

Who is that masked man? (subject)

The men, four of whom are ill, were indicted for fraud. (object)

Answer 4

If you can switch the person's name with him (despite if a girl) and it works....then use whom. If it does not work...then use who.

Answer 5

who is 'nominative' form used as a subject -- Who stole my chair?

whom is 'objective' and is used as direct direct object -- My chair was stolen by whom?

Answer 6

I think you can use either, it doesn't matter when, but i'm not sure.