Know your AP style: who, whom
Still struggling with who and whom? The AP Stylebook clears it up: “Who is the pronoun used for references to human beings and to animals with a name. It is grammatically the subject (never the object) of a sentence, clause or phrase.”
Whom, on the other hand, is used when a person is the object of a verb or preposition.
• Who is that?
• The man who was here last did not tidy up.
• The person to whom this belongs will be very grateful that you have taken good care of it.
• The woman whom frequents here is missing today.