Whoooo are you? Who? Who? Who? Who?

Who or whom?

Even native speakers of English have trouble knowing which one is correct: who or whom.

It's not that difficult, actually!
Se a resposta por um subject pronoun (I, he, they) usamos who.
-Who is she?
-She is my mother.

Se a resposta para a pergunta for um object pronoun (me, him, them...) devemos usar whom na pergunta.
-Whom do you love?
-I love him!

And here's a trick (truque) to remember:
Se a palavra termina em M (HIM) use WHOM!

And now a funny segment from that great series, The Office (you can tell Pam is right, BTW):


HERE is a good explanation and a list of pronouns, in case you get them confused.

And HERE is a quiz on object pronouns.