who vs whom

who vs whom
  Who and whom are both pronouns.
  Who is used to give further information about a person or people previously mentioned in a sentence.
  Basically anytime "I", "she" or "he" 'feels' right, who can be used.
  For example:-
  Lynne built that funny English website.
  She is the person who built that funny English website.
  In questions who is used when asking which person or people did something, or when asking what someone's name is.
  For example:-
  "Who is that woman over there?" - She is the boss.
  "Who let the dogs out?" - I didn't do it, he did!
  "She asked me if I knew who had got the job. I had to tell her she hadn't got it."
  To be honest, in informal writing and speech who is used most of the time, and poor old "whom" seems to be on its way out, but in an English test or exam, it's best to know when and where to use it.
  Whom is used in formal English instead of "who" as the object of a verb or preposition.
  For example:-
  "For whom the bell tolls."
  "There were 500 passengers, of whom 121 drowned."
  ♦ !Note - Whom is rarely used in questions. For example:
  "To whom do you wish to speak?" (This sounds very old-fashioned and stilted.You are more likely to hear "Who do you want to speak to?"
  ♦ !Note - If in doubt, try the "he or him" test:-
  Try rewriting the sentence using "he or him ".
  For example:
  "He took out a photo of his son, whom he adores." - "He adores he" should 'feel"'wrong. So it must be "He adores him."
  If you're still not sure and it's not an exam or test, go with who, 99% of the time you'll be right.

English dictionary of common mistakes and confusing words. 2014.