Do you ever wonder about who vs. whom? Which one should you use and when? The rules can be confusing and many people have trouble deciding whether to use who or whom. All you have to remember is who is used for the subject (of the sentence or the clause), and whom is the object of a preposition. You look for a preposition in order to decide.
When you're trying to decide whether to use “who” or “whom,” ask yourself if the answer to the question would be “he” or “him.” “Whom” and “him” both end in “m,” so just remember that if you can answer the question with “him,” use “whom.” If you can answer the question with “he,” use “who.
This silly photo pretty much sums it up. Who is always a subject and whom is always an object.