Who are you?

Confused about when to say who and when to say whom?
Good: it’s complicated.
First of all – only say who and whom when talking about people.
Here’s the rule: use who when you are talking about the subject of a sentence; use whom when you are talking about the object of a sentence.
A trick: if you would switch the question for the pronoun he/she/we/they use who; if you would switch the question for the pronoun him/her/them/us use whom.
Like this:
• He likes tomatoes. Who likes tomatoes?
• Lisa (she) uses Windows Live Messenger. Who uses Windows Live Messenger?
• We aren’t providing multimedia support in the product. Who isn’t providing multimedia support in the product?

• Einam is having lunch with him. With whom is Einam having lunch?
• They really appreciate the tech support team (them). They appreciate whom?
• We spoke with their sales woman (her). With whom did you speak?

Advice: While I haven’t actually researched this, I think that most of today’s English speakers say who almost all the time.
That doesn’t mean it’s correct, but it does mean that if you’re not sure and you say who, it’s unlikely anyone will correct you or laugh at you.
Whereas whom has become so infrequently used that it’s beginning to sound a bit archaic (like thus and hence, but I’ll save that for another week).