“Whom” is fancy and “who” is regular — right? While a lot of people think that’s the case, there’s actually a grammar rule behind when to use “who” vs. “whom.” There’s nuance to this issue, but “who” and “whom” are both pronouns. “Who” is used to refer to the subject of a sentence, and “whom” refers to the object of a verb or preposition in a sentence.
An easy trick to understanding which word to use is to answer the question using other pronouns. If “he,” “she,” or “they” works in the sentence, then “who” is the correct form.
Who is going to the fair? → He is going.
Who wants to know? → She wants to know.
If you can answer the question using “him” or “her,” then you’re dealing with object pronouns, and “whom” is the correct form.
Whom should I go out with? → You should go out with her.
Whom does the car belong to? → The car belongs to him.
For a mnemonic device, put aside the true context of the question and use “him” — if it sounds correct, then the “m” in “him” matches up to the “m” in “whom.”
Source: Wordsmarts
