Use "whom" when the pronoun serves as the object of a verb or preposition. The object receives the action or follows a preposition.
Examples: "To whom should I give this note?" or "From whom did you receive advice?" Here, the pronoun refers to someone receiving an action or following words like "to," "from," or "with."
Simple Test for Who vs Whom
Try substituting "he/she" for "who" and "him/her" for "whom." If "he" or "she" fits, use "who." If "him" or "her" fits, use "whom."
This connection to adjective clauses helps you understand how pronouns function within complex sentence structures.