WHO and WHOM

“Whom” is the object form of “who”. We can see this in relative clauses, for example:

1. “The person who owns this book would like it back.” In this sentence, “who” is the subject of the relative clause “who owns this book”.

2. “The boy whom they beat up has made a police report.” In this sentence, “whom” is the object of the defining relative clause “whom they beat up”. The subject of that clause is “they”. However, in this sort of sentence, it is possible to use “who” or “that” instead of “whom”, or leave out “whom” altogether:

“The boy (who/that) they beat up has made a police report.”

3. “Her aunt, whom she loves very much, is in hospital.” In this sentence, “whom” is the object in the non-defining relative clause “whom she loves very much”. In less formal usage, “who” can be used instead of “whom”: “Her aunt, who she loves very much, is in hospital”.

In modern English, “whom” is considered very formal. One common use of “whom” is in the expression used in a reference or testimonial written for a scholarship applicant or job-seeker, i.e. “To Whom It May Concern”. But in questions, “who” is more often used, e.g. “Who did you give the book to?” instead of “To whom did you give the book?”