Dya and Soheil's answers are both very good. In case it helps someone, I'm adding my own little trick for remembering which to use. I pretend that the answer to the question I want to ask is a male in third person singular: - Who spilled the milk? He spilled the milk. (Who? He.) - Whom did you tell? I told him. (Whom? Him.) - Do you know who called this afternoon? I know that he called this afternoon. (Who? He.) - Whom is the present for? The present is for him. (Whom? Him.) Of course, the actual answer may not be "he" or "him" - this is just a way to to keep the grammar straight. And this only works if you have a pretty good grasp of which male 3rd-person singular pronoun to use. :)

Hi! "Who" is used as the subject/doer of a sentence: 1. There are people who think English is too difficult to learn 2. There's a man in my neighborhood who runs 15 miles a day. But "whom" is used as the object of a sentence or after a preposition: 1. There's a man whom people call The Strider. He's a dangerous guy. (In this sentence "who" is also acceptable but less grammatical) 2. To whom am I speaking, please? ( For when you're on the phone) *

You're welcome! Have a lovely day. :)

Thank you Dya!

Good timing! I was just reading up on the best way to articulate this to someone else. The difference between who and whom is exactly the same as the difference between I and me , he and him, she and her, etc. Who, like I, he, and she, is a subject – it is the person performing the action of the verb. Whom, like me, him, and her, is an object – it is the person to/about/for whom the action is being done. http://www.elearnenglishlanguage.com/blog/english-mistakes/who-vs-whom/