How to Use "Who" and "Whom" Correctly

1.Know the difference between who and whom. 
They are both pronouns but who is used as the subject of a sentence or phrase and whom is used as the object of a verb. What follows is a quick way to determine which pronoun to use in a particular question.

2.Use whom when referring to the object of a verb.
◦To whom it may concern:
◦To whom did you talk today?
◦Whom does Sarah love?

3.Use who when referring to the subject of a sentence or phrase.
◦Who brought the paper inside?
◦Who talked to you today?
◦Who went to dinner?

4.Ask yourself if the answer to the question would be he or him. 
If you can answer the question with him, then use whom. It's easy to remember because they both end with "m". If you can answer the question with he, then use who.
◦Example: A suitable answer to the question, "To [who or whom] did the prize go?" is, "It went to him." (Almost no one would say "It went to he.") The correct pronoun for the question is whom.
◦Example: A suitable answer to the question, "[Who or Whom] went to the store?" is, "He went to the store." (Almost no one would say "Him went to the store.") The correct pronoun for the question who.