Correct use of who and whom is something that, in my humble opinion, will elevate your spoken and written English above the vast majority of native speakers.
This is one of those distinctions in English grammar that is so frequently used incorrectly that people seem to have become accustomed to using who even when it's incorrect. After all, if you're the only one who says whom when it's appropriate, people are inclined to think you're a bit pretentious.
That said, just because most people use who/whom incorrectly, doesn't mean you have to!
So, What's the Difference?
Who and whom are both pronouns.
When you’re referring to the subject of the sentence, use who.
When you're referring to the object, use whom.
NB: Sometimes you may have to break the who or whom rule to make your content more readable. Or, to prevent awkward and unnatural phrasing.
You should use whom to refer to the object of a verb or a preposition.
A simple trick:
If you can replace the word with “he” or “she” then you should use who.
However, if you can replace it with “him” or “her,” use whom.
Remember: The “m” in him goes with the “m” in whom. If you can answer the question with him, then use whom.
2.05 Assessment
Complete the 2.05 Who vs. Whom worksheet and submit for grading