Who and whom

Use "who" when it is the subject of a verb. Use "whom" when it is not the subject of a verb. (Explained below)

1. The word "who" can only be used when it is the subject of a verb.

Examples:

Who paid for the meal?

("Who" is the subject of the verb "to pay".)

I have not seen the man who lives in the hut by the beach for a week.
("Who" is the subject of the verb "to live".)

I wonder who is in charge.

("Who" is the subject of the verb "to be"; i.e. "who is".)

Sarah gave the tickets to who?

("Sarah" is the subject of "to give", but "who" is not the subject of any verb.
Therefore, you cannot use "who". It should be "whom")

Do you know the boy who rang the bell?

should be 'who' (subject of the verb existed)
(TV listing in magazine)

           should be 'who' (subject of 'will notify')
                            (notice in office)

2.   There is often confusion about when to use "who" and "whom". If you are unsure which to use, you should always use "who". Firstly, it is much more common than "whom" and, secondly, the use of "whom" is considered old fashioned in some circles. However, the ruling is that "whom" is never the subject of a verb; whereas, "who" is always the subject of a verb.

Examples:

You sat by whom all night?

(In this example, "whom" is not the subject of any verb. "You" is the subject
of "to sit".)

She is a wistful recluse whom lives near the river.

("Whom" cannot be the subject of the verb "to live". It should be "who".)

Claire saw whom yesterday?

(In this example, "whom" is not the subject of any verb. "Claire" is the subject
of "to see".)

Kelvin was with whom?

3. Always use whom after prepositions. Prepositions are words like "to", "with", "by", "on", "in", "near" etc. (See lesson "Prepositions" for more information.) "Whom" is always used after a preposition. (This is because it cannot be the subject of a verb.)

You have a child by whom?

With whom did you see Janice?

should be 'by whom'
(advertisement by estate agent)

That is the lady to whom I made the promise.

That is the lady whom I made the promise to.

(This is the same as the one above. Ideally, you should not
end a sentence in a preposition (like "to"), but sometimes it
sounds better. The word "to" still governs "whom" even
though it is at the end of the sentence.)

With whom did you go the cinema?

Who did you go to the cinema with?

(Even though the second version ends in a preposition, it is easier on the ear. This subject is covered more in the lesson on prepositions.)

Funny? No. It should be "Two hits to whom?"
("joke" in a student comic)

SUBJECT OF A VERB?

Verbs are doing words like "to dance"," to sit", "to fly", "to think" etc.) (See lesson "Verbs")

The subject of a verb is the person or thing that is doing the action.

Peter flies to Moscow on Tuesdays.
("Peter" is the subject of the verb "to fly".)

Helen's boss drinks like a fish during the day.

"WHO" EQUALS "HE" (A NEAT TRICK)

Substitute "who" with the word "he". If that part of the sentence still makes sense, then "who" is almost certainly correct. (These are from the examples to the left.)

He paid for the meal. (< sounds ok)
("Who paid for the meal?" is correct.)

...he lives in the hut... (< sounds ok - "who" is correct)

...he is in charge. (< sounds ok - "who" is correct)

...to he? (< does not sound ok - "who" is wrong)

"Who" and "he" are always the subjects of verbs. They are said to be in the "subjective case". This is why the trick works.

"WHO" EQUALS "THEY"

In order to perform this trick for plurals, you will have to substitute "who" with the word "they".

I met the people who were on the plane.

...they were on the plane. (< sounds ok - "who" is correct)

"WHOM" EQUALS "HIM" (A NEAT TRICK)

Substitute "whom" with the word "him". If that part of the sentence still makes sense, then "whom" is almost certainly correct.

Sarah gave the tickets to whom?

Sarah gave the tickets to him. (< sounds ok - "whom" is correct)

("Whom" and "him" are never the subjects of verbs. They are said to be in the "objective case". This is why the trick works.)

"WHOM" EQUALS "THEM"

In order to perform this trick for plurals, you will have to substitute "who" with the word "them".

The witness saw four boys, one of whom had a limp, leave the shop.

...one of them had a limp... (< sounds ok - "whom" is correct)

Associated lessons:

What are pronouns?
The object of a preposition