1. Who vs. Whom

2. Who and Whom These pronouns are both:
interrogative pronouns (used in asking questions)
and relative pronouns (used to refer to a noun in the main clause).

3. Who is the Subjective Form
Who is always a subject doing the action.
Use who whenever he, she, they, I, or we could be substituted in its place.
Test it: If you could use he, she, or they – then use Who

4. Whom is the Objective Form
Whom is an object—receiving the action
Use whom whenever him, her, them, me, or us could be substituted as the object of the verb.
Test it: If you could use him, her, or them – then use Whom
Clue: If it follows to, for, from, or by
use whom