What are the grammatical usage tools for who and whom?

Answer by  Vicki (14)

Who is used as the subject of a verb and whom is used as a direct object. Whom is also frequently used as as part of a preposition and will be coupled with "to", whereas you would never say "to who."

Answer by  John (9008)

"Who" is used for the nominative case, which generally means as a subject in a sentence. For example, "Who is it?" is correct usage. "Whom" is used for the objective case, which usually means either a direct object or the object of a preposition. For example, "For whom are you calling?" is the correct use.