Deciding whether to use who or whom has plagued people for years. Quite often it is only touched upon in grade school and in high school teachers may automatically assume that their students are familiar with the correct grammar usage of who versus whom. It can be exceedingly tough to gauge when to use the correct word. Below is a brief explanation of the correct usage according to English grammar rules.
First and foremost it should be said that who and whom are both pronouns. That is right, the two words in question belong to the same "I-you-he-she-it-we-you-they" family. With this notion in mind it should be a bit easier to digest the proper usage of either word.
The word "who" refers to a subject and the word "whom" refers to the object of a clause. Not just an object but the object of a clause. So, if you think in terms of people doing something then:
An easy way to remember when to use who and when to use whom is to think about the following rule.
Whom is normally used in formal English only. The contemporary usage rules seems to favor using the word who in either situation (subject or object-wise). The contemporary usage rules of both who and whom are quite often the subject of debate on many college campuses. So much so that it would not be uncommon if a student learned one usage rule in high school and was taught something completely the opposite in college. There is still much discussion on many grammatical levels on the subtlties and nuances of when and how the who/whom usage rules apply and when such rules can be ignored.
Depending on the college (or university) and how strict or lenient the grammarians are within that college (or university) the grammatical rules surrounding who/whom may be strictly adhered to, or moderately bent to suit the regulations of the college. This also occurs in various job settings where there are manuals written on the grammar guidelines as observed by that particular company. This can be seen in many government agencies where standard English/grammar guidelines are tailored to meet the innate editorial needs of that particular government agency.
It seems as if the usage debate over the words who and whom will always be in tow, until new grammar guidelines are set forth for students and professionals alike. If you are currently experiencing confusion over when to use who and when to use whom, it is probably best to simply follow the current usage rule, that is, unless you are attending a college or university where the grammar rule has been altered, or if you are working in a position where the professional writing manual stipulates otherwise.