To Whom It May Concern:

Let me help you with one of those heavy, difficult questions life offers up from time to time: one must use "who" when supplying the subject, "whom" when the object of a sentence. This is much easier to remember than switching out other pronouns (he/him, she/her, etc.) to see what fits.

SUBJECT? WHO.

• Who left this unicorn in my garden this morning?
• Who is responsible for letting the bats into my belfry?

OBJECT? WHOM.

• This tatty old sock belongs to whom?
• You need my spyglass to attend the opera with whom?

However, I must allow that this gets a little tricky sometimes, for often who/whom sentences are, by nature, arranged confusingly. This is when it becomes extra-important to understand what a subject is and what an object is. the subject acts, and the object is acted upon. It's less about where in the sentence the words are and more about what is happening in the sentence.

Some of us had, at some point in our academic careers, teachers who taught us to swap out the words who/whom with the words he/him (or she/her, if you will) within the sentence to find the appropriate usage. Personally, I feel that's still way more complicated than necessary and will lead to further confusion in the form of nonsensical sentences. If one needs a pencil and paper to practice one's queries upon before putting them to one's interrogee (okay, yes, I made that word up--sue me), then one will have wasted precious investigative time and energy.

Allow me to simplify. Look instead for the answer to the question. If the answer will be him/her, use whom; if it will be he/she, use who. Who? He. Whom? Him. For example:

• Who/m is going to cook the holiday turducken this year?

Obviously, the answer will be that HE shall cook the turducken and not that HIM will cook it. (Also, because turducken is such an abominable and blasphemous creation that SHE will certainly not deign to prepare it, but I digress.) Thus we find that the appropriate pronoun for this sentence is who.

Let's look at another example of the opposite inclination:

• Who/m would you like to receive your complimentary hand-knitted cat hair yarn purse?

The answer must be that I would like him or her to receive the craftastrophe in question, and thus we will use whom... by the grammar rules, that is. I just need a moment to decide whom it would most please me to drop that special delivery upon.

...and yes, such a thing really does exist, as do unicorns, bats, and turduckens.