When to use "Whom"?

Question

Hi. English is not my mother language and I really don't know in which cases I have to use "Whom" instead of "Who". Could somebody explain that to me?

Answer 1

"Whom" is the objective form of "who" and is used, for example, as the object of a sentence or more commonly, the object of a preposition.
"With whom did you go to the mall?"
"I went with him."
Note here, both whom and him are the object form of the subject pronouns who and he.
Well, that said, in speech, often the use of "whom" is ignored and the subject form is used. Most native speakers would have no problems if you said, "Who did you go with?" although technically it is incorrect. But often use supersedes correctness.

Answer 2

After a preposition the English grammar demands that "whom" be used: to whom, for whom...

Answer 3

Who is used in subject position, whom is used in object position. After a proposition whom usually follows.

e.g. Who knows grammar? To whom are you married? Who is fooling whom?

Answer 4

who is generally used when its the subject/noun of that sentence. whom is used when its not the subject.

Answer 5

simply, after a preposition