The words who and whom are pronouns.
Who is the nominative (or subjective) form, it means we have to use it when referring to the subject. Every verb has a subject. The subject is performs the action. Who------Performs the action
Whom is the objective form, it means we have to use it when referring to the object. Some verbs have objects. The object receives the action.Whom-----Receives the action
Correct: Who brought the paper inside?
Incorrect:Whom brought the paper inside?
Correct: Who talked to you today?
Incorrect:Whom talked to you today?
Correct: Who went to dinner?
Incorrect:Whom went to dinner?
Both who and whom can be used to introduce dependent clauses. I would like to remind you that the words who and whom depend on the function of the noun it represents, or its antecedent.
The following example gives you a clear idea when to use who and when to use whom.
The man with whom she attended the meeting, is her husband.… [object of with]"
The man whom she met at the meeting was her old boss.… [object of met}
The man who came to the meeting was known to her.… [subject of came]
It were they who awarded the trophy.
Whom should I send the check to?
Who should receive the check?
Whom do you wish to speak?
The issue of who is at fault has yet to be decided.
Vote for the candidate who you think will do the best job.
She plans to grant the contract to whoever bids the lowest.
Throw the ball to whom you please